While SEO can become a highly customized process taken on a per-site basis, there are of course a few general guidelines that are used universally. No matter what your site is about, or how it is setup, there are some basic steps most webmasters should be aware of when it comes to SEO.

Semantic (x)HTML Code
Depending upon when you started learning HTML, you may be accustomed to styling text HTML formatting tags. For example, the following will style some text

<font face='arial' size='5' color='blue'><b><i>Hello World!</i></b></font>

The above code is not actually valid XHTML, though it is valid HTMl, and will still likely show up in all browsers as large, blue, bold and italic. The problem is, spiders don't actually know if this is important text or not - you're just using a font tag to style it different from other text. Rather than the above code, the following should be done

<h1>Hello World!</h1>

You can then use CSS to style this however you like. Spiders will realize this is a heading tag, and h1 tags are given very high weight when determining important keywords for your site. Similarly, other tags should be used appropriate: p (paragraph), strong, em (emphasis), blockquote, cite, link, meta, and so on. b (bold) and i (italic) tags are formatting tags, and you should be moving away from them and using CSS instead. By using tags appropriately, spiders can parse an (x)HTML page properly and determine the important stuff eaiser. Additionally, by moving formatting out of the page, you increase your chances of the spider keeping caches of your page (the less HTML there is, the smaller the page, the more likely they are to keep a larger number of your pages in cache) which will generally help search result listings as well.

Using and Structuring Keywords/Keyphrases Properly
Keywords are words on your page that are used to determine what your page is about. Similarly keyphrases are collections of words (phrases) that are used to determine what your page is about. These keywords and keyphrases are what you would type into a search engine query box.

You want to ensure your pages properly use keywords and keyphrases related to your site in appropriate places. Place important keywords/phrases near the top of your page. Put them inside h1 tags where appropriate. Try to ensure when people are linking back to your site, they use these keywords and keyphrases in their anchor text (this has, arguably, the highest weighting in determining what your site is about and how to list you in search result listings when linked to from a "good" site). Make sure the keywords and keyphrases accurately describe your site, the discussions on your site, and so on. Do not try to use underhanded tricks to get them on your page, such as hiding the text in a hidden div, or with the same font color as the background color. If you are knowledgable and skilled enough, try putting the important phrases inside a div near the top of your page, and using CSS (or javascript, if necessary) to position the div where you actually want it to show up - the higher up on the page these keywords and phrases are, the more weight they are given.

If you are creating your pages for humans, and not spiders, the keywords and phrases should come naturally, and be used in the normal context of the page, without having to do anything really fancy or tricky. The keywords should be short and concise, and accurately describe what your page is about.

At the end of the day, the goal is to make sure spiders know what your site is about - don't leave them guessing. Using semantical code, as described above, will help tremendously. Also, picking your keywords properly (instead of using "car", for example, use "mustang" and "ford mustang", if that is what your site is about) is very important too.

Sending Proper HTTP Headers
When using a dynamic system (such as a forum system, e.g. IPB) most of this is either done for you, or beyond your control. However, this is still an important general guideline that should be pointed out.

Sending proper http headers is very important - it tells a bot what to do and how to behave.

• If a page is missing, your server should be sending a 404 error message to indicate this to a spider.
  
• If the page will render fine, of course you should be sending a 200 OK http header (sending no header on most web servers when printing HTML will cause the server software to automatically send a 200 header).
  
• If the page has been moved permanantly send a 301 redirect header. This is very important - sending a 404 will tell the bot the page no longer exists. Sending a 301 header will tell the bot to update it's links, so you don't lose all your backlinks, page rank, and so on.
  
• If the page has been moved temporarily, send a 302 redirect header. This is used less often than a 301 header, however if the situation fits, use this properly. Because 302 redirects indicate a temporary status, bots will not update their link weighting and backlink references when this status is encountered, so this should rarely be used, as it generally hurts more than helps.
  
• If there are duplicate copies of a page (or multiple urls to reach the same page) send a 301 redirect from all of the pages (except the "real" url) to redirect to the actual permanant url you want to be indexed - this will avoid duplicate content penalities, and will ensure all the backlinks and references are weighted to one page, rather than spread across multiple copies of the same page.

The goal is to make sure spiders know where to go and what to do on your site. Sending the right header for the right situation is important in achieving this goal.

Pick a URL Scheme and Stick to It!
While it is widely agreed upon that static URL's (those than end in .html or .htm) are preferred over dynamic urls (for example .php or .asp, or urls with query string arguments) it is also true that bots DO index dynamic pages. Don't change just for the sake of change.

However if you are setting up your site anew, or are trying to implement an SEO package in one go, using mod_rewrite on your site can help, and using static urls is recommended.

Firstly, if you are changing an existing structure, make sure to 301 redirect the old requests to the new urls. We cannot stress enough how important this step is - otherwise you end up with duplicate content and backlink reference weights pointing to the old dynamic urls that are not applied to your new static urls (which will have lower rankings than they should). You should also ensure, either through your mod_rewrite configuration or in your application directly, that you cannot access the page through multiple urls either. For example, a common mod_rewrite setup might be to match some numbers in a given url structure, and use that to determine the dynamic url to generate. For example, take the url http://somedomain.co...my-page-t50.htm. You might have a mod_rewrite setup that looks for the following (note, this example is actually taken from CommunitySEO [for IPB]).

RewriteRule ^(.*)[-_]t([0-9][0-9]*)\.html(.*)$ index.php?showtopic=$2$3

As seemingly harmless and proper as this appears at first glance, what do you think will happen if I try to visit this url:

http://somedomain.co...us-url-t50.html

I will reach the same page. No harm done right? WRONG! Sites that don't want to see you do well (basically, everyone competing for better positioning for the same subjects/themes) can link to you using the "incorrect" urls thus creating duplicate content on your site. It is important to ensure your pages are accessible via one url only, and that other requests 301 redirect to the correct URL.

CommunitySEO software has the ability to do the above, configurable via the settings in the Admin Panel.

It is also important to spend some time determining what keywords to include in a url, what words (if any) you want to strip (usually "stopwords"), whether to use dashes or underscores (typically, dashes are recommended), how long to make the URL's, and so on. The end goal is to get one url pointing to each page, and not change it.

Meta Tags and Link tags
Meta description and keyword tags have largely lost their weight and importance, and are barely worth the time to implement - however a few search engines will still use some of this data to help determine how to display your listing on their search results page, even if they don't use the tags to determine how well to rank your site. Because it only takes a few moments to add description and keyword tags (don't spend more than 2-3 minutes per page) you should still add them.

We've seen good results when setting your title, description, and keyword tags the same, as typically the same information should be delivered in each tag anyways. As with all SEO, there are many factors that affect your rankings, so keep in mind your milleage may vary.

There are dozens of OTHER meta and link tags, however, that can help tell spiders how to behave, or deliver other important information about your page, so research them and determine which to include and which to skip.

Get Links to Your Site From Other Important Sites
Links to your site, especially when they use proper and relevant anchor text, are among the highest weighting factors used by search engines. If other sites related to the same subject as your own are linking to you, they must have felt there was something on your site that their visitors might benefit from right?

Regular affiliate and link exchanges are good, however, many search engines can indeed pick these out from regular backlinks used in normal context. For example, if there is a block of code like

<h4>Check out our affiliates!</h4>
Some link here
Some other link here
Your link here
...

A spider will realize this is a list of related resources, however that the link is not directly related to the context of the page specifically (in most cases). However if a spider is parsing a paragraph of text on that site and comes across

And I found a great article describing <a href='http://yourdomain.com/somepage.htm'>how to change an alternator for my 91 Mustang</a>

The spider realizes that the site is linking to a direct page on your site describing how to change an alternator (for a 91 mustang of course). When someone searches for terms like "alternator mustang" and "how to change my mustang's alternator" it is going to rank your site a little higher, due to that backlink.

The weight and rankings a spider will grant your site based on references and backlinks will vary greatly, depending upon the site, how important the site linking to you is, how the link is generated, and so on. However, the more backlinks (from reputable sites) the better. This is probably the #1 thing that can help you move up in search engine result listings, while at the same time is still somewhat beyond your control.

Content a Spider Can't Read
You should attempt to ensure that for every content resource on your site that a spider can't read, that you provide an alternative. For example, there is a noscript html tag that can be used to send something to a browser when javascript is disabled (which it is mostly for search engine spiders). You should use alt tags on images to give a description of the image (do NOT stuff keywords into alt tags - this hurts the page for visually impaired visitors, and spiders pick up on this 'trick' quite easily) so spiders know what the image is intended to indicate. You should have an alternative for any flash content you place on your page.

At the end of the day, if the spider can't see it, and also can't determine what it is or what it is there for, it's not going to help you. If you are putting important information and content inside a flash movie, that is content that a spider will not be able to index, so make sure you balance "appearance" with "usability" wisely.

Use a Sitemap
If you can add a sitemap to your site, and link to it from every page, this can help spiders index more of your site quite effectively. A sitemap should be a simple, slimmed down page that has links to every page on your site. This is like hitting the lottery for a spider - rather than having to go page by page finding other pages, it can go to a central repository and instantly have links to every page on your site. An HTML-based sitemap is a great idea, because it is compatible with all search engines (you can consider the Lofi pages in IPB a sitemap of sorts). A google sitemap is also a good idea, because it will tell Google exactly where all of your pages are (and you can even tell Google the last modified date of the page, how often it changes, and indicate how important the site is in relation to the rest of your site). You should be sure to submit your sitemap to google if you generate a google sitemap.

CommunitySEO has support for generating Google sitemaps automatically for you.

When creating a sitemap, think about your human visitors too - this is a valuable tool for someone trying to find their way around your site, so make sure it is accessible, and effective.


And Just a Final Note
Everything you do for your site to optimize it for search engines should be secondary to optimizing your site for human visitors. We can't stress this enough. Search Engines are important yes, but if human visitors can't navigate your site, or if it is inaccessible to various groups (for example, users on PDAs or cellphones, or visually impaired persons) it won't matter how optimized it is for a search engine, because the human visitors you are trying to drive to your site will just leave if they can't navigate around.

By optimizing your site for human visitors FIRST, you are laying the fundamental groundwork for good search engine optimization at the same time. Using proper url structures helps humans remember the url to your site, and helps them to remember what a site is about when looking at it in their favorites. It also helps a spider determine what the page is about at the same time. By using keywords to describe an image in alt text, you are helping to ensure visually impaired persons (who often use browsers that read the text to them aloud) can know what an image is intended to represent - at the same time you are helping a search engine spider know what the image is about as well.

Spiders are becoming increasingly advanced and complex, and many of them are starting to pick out spider-specific tricks used. Don't be underhanded, and don't concentrate on spiders first, and humans second. You will find yourself in more trouble down the road, than if you concentrate on the really important visitors - the people you want driven to your site to begin with.

The most widely made SEO mistake is the use of graphic headers at the top of a webpage. Remember, the top portion of a webpage is where most of the keywords must come in for best SEO. If that space is used instead for some logo or other catchy images, while it leave the webpage good looking, it does not help search results in any way. The same is the case with graphic navigation menus. The search engine won’t be able to index the text contained in its links

Most common mistake SEO's do is trying to improve rank for every single web page. You don’t want your privacy policy or user login pages to rank and when they do, they use up site authority that should be channeled to pages that are designed to attract new visitors. Each site only has a limited amount of authority to spread around, so you don’t want to waste it on pages that don’t drive business. Use commands such as robots.txt and nofollow tags to exclude pages that aren’t meant to generate new business and pick a few pages to be your specific SEO targets. Give each one its own focus and strategy.