By this point you should have covered the following
1. Know where you are going
2. Sorted out basic issues with your site and pages
In short you are now no longer disliked by the search engines for being unreliable, confusing, difficult to read and poorly presented.
The next step is to get the search engines to like you and potentially like you more than they like your competitor's websites.
We'll be looking to give your website and pages two factors.
Just before you begin to optimise you should hang fire. If Google webmaster tools shows that it has no idea of your website's existance before you signed up then you are ready to move on straight away.
Alternatively you may see that Google was very aware of your site and you are well ranked in the search results for words you were not even aware of. Now before you go changing everything stop to consider if there is some way to take advantage of this situation.
You may have accidently become well ranked for a keyword or phrase that others are fighting over tooth and nail and you may be able to use this to your advantage so don't miss this opportunity!
I'm Tim Hill, a Search Engine Optimisation and Online Marketing specialist. I created this site to help others understand that SEO is not a mysterious black art!.
If your a newbie try the Getting Started in SEO page, otherwise feel free to dig around and learn more.