Don't get overwhelmed by set up, find a sheet for your car by a top driver for either the same track or a similer track and concentrate on tires and ride height being in the zone and work on driving more than anything... slower with smooth tight lines and getting a driving rythm is key to learning to race.
The one that got me when learning about a car is how important it is to look after shocks, regular re-oiling and keeping an eye on the seals (When the oil is dirty, replace those seals!). Shocks are key.