1. get a normal, neutral setup (either from the manual or from someone who knows what he's doing and who knows you are a beginner) and a normal not too fast motor!
2. practise with that untill you can run at least 5 minutes without mistakes. Doesn't matter if your laptimes are slow. Practise on your own can help if you have to run down the rostrum each time you make an error, you'll learn quickly to stay on your wheels
3. go to clubraces and then try to race for 5 minutes without mistakes
You'll notice it won't be so easy as in practise
4. watch the fast guys drive, go stand on different sides of the track and look at their lines. But especially, listen to the sound of their motor and be amazed how easy they go on the throttle (especially on clay)
5. try to copy this driving style---->practise again!
When you can race for 5 minutes without mistakes, then go talk to other people trying to change your setup. 1 change at a time! If you don't feel the change, or you are not sure it is better: put it back the way it was and try something else. Write it all down each time you change something, and also make a note about how much effect it had. In the end, you will know which settings have a drastic effect, and which are only minor changes, finetuning.
At a race, don't just look at your fastest lap. Take a look at you best 3 or 5 laps, count how many laps you have in the same second as your fastest lap etc... If a setup change only changed your fastest lap, but you ended up on your roof 5 times, change it back...
Slow=fast. That doesn't mean you need a slow motor, it means you need to go slow into a corner, and fast coming out of it. If you carry more corner speed, in other words your car doesn't lose all the speed at one point in the corner, you don't need to accelerate that hard getting out of it, and your car will look more stable. Usually you never need to brake very fast and hard, or accelerate very fast. When coming out of a corner, accelerate gradually, steer gradually etc...
This is an onboard video of some decent laps at kampenhout in Belgium:
http://youtu.be/Js-i8SgnAuM?hd=1&t=4s
Listen to the motor and brake sounds, take a look at the servo link, it's all relatively 'smooth'.
If you are comfortable with your car, and you know a bit how to set it up, what I found that helps a lot is driving with a laptime beep on your transmitter. This beep goes off every x seconds, so for example if your fast lap is around 25.0, set the laptime beep to every 25.5 seconds. Start the timer in your practise run for example right after a jump, then sart driving and try to be right after that jump again next time the beep goes. If your further on track, you are running faster laps, if you are behind on track, you are running slower. The goal is to do lots of laps and traying to stay ahead or at the same point as the laptime beep. This helps a lot in trying to be fast and consistent at the same time. Plus, you immediatly now when you had a very good lap if you gained on your beeper, and you usually know what you did well or bad in that last lap.