SEO Tips

You must get indexed by the search engines, most offer a method to submit your site, however its FAR better to simply get a linkback from another website. Let them find you naturally.
Keep the text between the title tags under 50 chrs - This will help you get the most out of your keywords
Avoid using dynamic URLs (eg: http://www.example.com/index.php?id=123) use static looking links instead (eg: http://www.example.com/example-articles.html) -- Also avoid PHP session IDs and unnessisary variables.
Register your domains for longer than a year - spammers usually only buy domains for 1 or 2 years.
Larger, older sites are better.
In search engines "the-word" usually registers as "the word", so where possible use - (dash) instead of _ (underscore) in your URLs
Choose a domain that will be most relivant to you, either your name (product, company, business, etc) or descriptive (eg: search-engine-optimisation-example.com)
Dashes in URL (eg: http://www.search-engine-optimisation-example.com/the-home-page.html) -- stick to no more than 4 in a URL.
Keep your URLs short, less than 100 chrs is best.
Unique description meta tags per page - less than 200 chrs, although search engines don't rely on this, it is often displayed
Unique keyword meta tags per page - less than 10 words, the keywords must appear on the body text of the page, no repeats
Make use of the header tags (H1, H2, H3) these will help idenify what the page is and push your page further to the top
Place your keywords in your body text near the top, try and use b (bold), strong (bold) or em (italics) on them.
By internet standards all images must have alt text - Describe the image using short relivant text.
Use keywords for your link anchor text instead of using "click here" or such.
External links per page should be a limited to 100 where possible.
Choose your domain name TLD extention carefully, .edu and .org appear to get higher status than .com due to spam.
Size of pages should not be larger than 100K, its prefered that you have lots of smaller pages.
Search engines like updated pages, such as news pages, it also like additional pages, make sure you also keep your old static pages.
Site consistancy -- althought its not proven to be a factor of SEO, it does help usability.
Search engines like blog sites as they bare lots of content and many external links, showing trends
Use text instead of images where possible. If you have to use images, use alt text. - Search engines don't read text on images.
Get listed in directories such as DMOZ and Yahoo, avoid link farms and FFAs.
Avoid using meta redirect to redirect users to other pages.
Avoid excessive cross-linking to sites hosted on the same IP range (C class).
DO NOT copy your content. Not only does this violate copyright laws, search engines penalise you.
Search engines find it difficult to get relivant text from Flash if any at all, avoid contructing your page with flash, unless its for presentational purposes.
Search engines don't follow links in forms, image mapping, javascript links, frames, very well, if not, not at all.
Avoid putting your email address in text form on a page, as this will appear in search engines and generate unwanted emails
Avoid any "black hat" SEO methods, they don't work in the long run, stick at the real methods and you'll get far better results than risk your site getting banned.
Use correct HTML markup where possible, although this doesn't make much of a difference to the search engines, it will help you avoid other problems.
Don't use gateway pages or intro pages, they are useless and tend to disappear from search engines, not only that but the main page gets pushed down. -- This is also bad for usability as visitors aren't interested in your gateway, just your website.
Try and get as many backlinks from as many relivant websites as possible. Avoid bad sites. -- Anchor text on your links is important here, make sure you use a relivant keyword.
Try and get people to stay on your site, avoid annoying the user and provide them with reasons to stick around.
Suggest the user bookmarks your page or create pages that would be bookmark worthy.
Use a stable web server, there is nothing worse than having your site down.

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