Below are my first few tweak tips that I have found has helped me. Hopefully you guys will join in and we can build up a nice list.
1) Rename your active theme folder to the keyword you are using. Example, the folder that holds my theme is called AdSense-tricks as thats the keyword I am targeting
2) Add your own theme info in the CSS file.
/* Theme Name: AdSense tricks */
Copyright © 2010 AdSense-tricks
The Green-Widgets is a link to your home page. The reason I do this is that I have read in other posts that Google likes the Copyright wording next to your actual keyword.
4) Rename your logo file in the top left to the keyword you are targeting. So my logo is named adsense-tricks.jpg
5) Hard code a ALT tag into the header for your logo with the tag as your keyword. So in my sites, if you hover over the logo in the top left my keyword, AdSense tricks, is shown
6) De-activate and delete from your site all unused plugins
Thats it for now. I will add some more later