I'm pretty active in my professional community as an SEO manager and usability expert. Occasionally I get asked the question, "How do I do SEO?" I usually suggest starting here:
Google's SEO Starter Guide
Google is the gold standard of search, which is why searching is referred to generically as "googling". Google wants better websites on the internet, and they want to show those sites to their searchers. If they can show better sites and better content to their searchers, that re-enforces Google as a quality search engine. So, when the king of search engines writes an SEO guide and you want to learn about SEO, READ IT! In fact, read it twice.
1. Don't be do "SEO". Often when many people say "SEO", what they usually mean is that they want "tricks" that will make them come up higher in search results. Usually when people try SEO tricks, their site ends up looking spammy and visitors generally get an "icky" feeling. Yes, you should do things like put keywords in your link text, but you were probably going to do that anyway. Why pay someone $185/hour to tell you something you already know?
2. Good quality content. All the SEO in the world is wasted if users don't like your content. If you have good content, users will share your site with each other. When people share your site, it builds your link popularity, which is more powerful than SEO.
My favorite sites on this subject are:
Copy Blogger
Zen Habits
3. Good usability. All the SEO in the world is wasted if your site is difficult to use. A site that has good usability naturally brings in SEO techniques. I'm sure that must sound strange, but SEO is quickly becoming the science of building a website with common sense.
My favorite sites on this subject are:
UseIt.com
Webpages That Suck
Be careful, when it comes to SEO, there are a lot of BS and scam artists who will sell you a big box of lies and bad practices that will get your site banned from the search engines. Of course, I have to plug myself, because I think that I write some pretty good material on SEO and usability
PageRank and Link Juice SEO Blog
Good luck,
Chris