To get a better base for the setups have a look a
www.gplea.org and download the Solitude track. This is where I start with my setups for each track (you load it in for each track and car). They are so good as the spring rates are set up right, and all you need to do is fine tune it for each track (ride height, arb, toe, etc) Also try to stay with a 85/45 diff and 6 clutches. Then it is just down to practice
Also if you have driven laps at all tracks have a look at
http://gplrank.schuerkamp.de/ when it is back up working and get a ranking. Then aim to get a negative rank, and it is harder than it looks.