Make sure you understand what SEO is all about before you read this. I am using Google as an example but the principal is the same across all search engines with the same type of algorithm.
- Build your site with the latest languages available, I.e PHP5. Why? Because Google looks at how technologically advanced your site is and whether it complies with theirs and W3C standards.
- Create Meta tags, but think about them thoroughly, make page specific tags so that Google can index specific pages for specific searches.
- Create ALT tags for all of your images.
- Have content that is relevant to a specific page, and make sure you do not overdo your keyword repetition because you will be penalized by Google.
- Create both human and XML sitemaps for your site and submit them via all the major search engines webmaster tools.
- Link your site properly, not only links out of your site, but also the structure of your site itself and how your site flows for your user. Please also be careful of who links to your site, they might not be relevant and have a very bad effect on your organic ranking.