1. Write Unique Title Tags for every page and include keywords in them.
2. Maintain a proper internal linking structure for your site.
3. Use text based navigation as far as possible.
4. Donate use images as heading etc. If you need to use a special font, use the font replacement technique known as sIFR. sIFR is meant to replace short passages of plain browser text with text rendered in your typeface of choice, regardless of whether or not your users have that font installed on their systems. It accomplishes this by using a combination of JavaScript, CSS, and Flash.
5. Create a site wide link to your home page in the footer of your site. What I mean by this, is in the footer, write a line like Copyright 2008 – 2009 Company Name, where company name links to the sites home page
6. Instead of using click here links, use links with keywords in the anchor text. This are helpful to both search engines and to people. Example: To learn more about seo, read this article on what is seo
7. Make sure that the site's code validates. It will help search engine spiders’ crawl your site better.
8. Wherever Images are used, make sure that they contain alt tags with proper descriptions.
9. The page name or URL must consist of the relevant keywords as it gives an idea of what the page is all about. Also, separate the words using hyphens.
10. Don’t overdo the use of graphics.
11. Don’t use tables to create your site. Use css instead. Css stands for cascading style sheets. Css pages take much shorter to load, and generally require less code.
12. Maintain an external style sheet. This helps search engines as well as you, incase you want to change the sites design later; it will be easier to do so.
13. If you use any images on the page, make sure that they are optimized.
14. Make sure that your page size is never greater than 65-75 kb. This ensures that your site won take forever to load.
15. Continuing with the previous point, make sure your site doesn’t take forever to load.

Some Bonus Tips on SEO and Web Design
1. Utilize Unique Meta Description Tags for each page.
2. Create A sitemap for your site
3. Make an account with Google Webmaster Central and submit your sitemap there.
4. Do the same thing with Yahoo and Bing
5. Use your keywords in bold and italic tags ( only sometimes )
6. Also use your keywords in heading tags.
7. Link to related pages on your site from other pages on your site. Thanks To My Sumber Articles