SEO breaks into 2 parts:

1) On site
2) Off site

On site SEO is about making it easy for the search engines to find out what your site's about and where to find specific information within it.

Here are some steps you need to take:

Firstly, fill out your META data fields and do that for each page on your site individually. These are the three most important fields:

1) Title
2) Description
3) Keywords

Here's a link to a free online resource for creating META tags:

http://www.htmlbasix.com/meta.shtml

Follow the instructions on that page.

Secondly, make good use of your h1 and h2 tags on each page.

Thirdly, make navigation of your site complete, clear and easy to follow.

Fourthly, create a sitemap - and here's a link to a free online resource for doing that:

http://www.xml-sitemaps.com/

Just follow the instructions they give you on that page.

Off site SEO is about getting quality inbound links to your site.

For that you can use article marketing, forum marketing, commenting on blogs and participation in Social Networking groups.

Avoid link farms, link exchanges, buying links or anything else that seems like a good idea at the time.

Of the things I've mentioned above only META data and sitemaps are targetted specifically at the search engines.

And even with the META data, both the page titles and descriptions are aids for people.

Everything else I've mentioned makes it easy for people to find and navigate your site.

The search engines are continually making changes to their algorithms, but the one thing that remains unaffected by these is the effectiveness of good quality content.

The point I'm trying to make is this:

Design your site for people. Write it for people. Make it easy for people to find your site, understand what your site's about, and find their way around it.

Designing your site so it's easy for people to find and navigate also makes it easy for the search engines.

And, most importantly, write good stuff. Fill your site with good content - that's what will attract and keep people there.

If you implement all these points on every page of your site you will begin to attract high quality traffic from the search engines.