I have been racing RC cars for almost 10 years now, and been doing okay i think
So i'd like to share my experience, with all you guys.
First the car:
Depending on your level, you don't want to use the setup from the absolute fast pro guys. Their setup is made to get the max out of the car, and thereby setting aside the driveability.
You can take inspiration from their setup, but mostly need to adjust to your own like!
That said, your setup needs to be well balanced, in the start slightly to the pushing side.
It's important that the back is stable, and must not step out of line while driving! The car must turn through the corner with both ends of the car, not by the back drifting wide or the front diving/digging to hard in.
The car must also drive balanced through the hole corner. If the car has to must steering out of the corner, compared to turning in to the corner, it will be hard to make nice controlled corners every time.
maybe ask some experienced guys to look at your car while you drive, then they will be able to tell if the car looks right while you drive. And let them try it, the will spot if the car behaves weird.
And as others has also said, your car must always be in a good condition. Clean the car after each run with a brush, and regularly check the setup, reglue tires, clean the tires and the dampers are very important, if there is air then change the oil.
Then on how you actually have to drive
Some basic things about driving into corners.
it's always better to get slow in and fast out! Never the other way around...
It's not faster to go fast through a corner away from the apex. Slower but closer to the apex is always better
The car only has 100% grip to use to go around the track. When you approach the corner you need to slow down. but if you brake and turn in at the same time, you use the 100% on 2 motions, turning an slowing down. This translates into both things not working very well... The car doesn't turn and doesn't stop. While braking go as straight as possible, according to the layout of the track, then turn after braking. This happens very fast, and it takes time to do it right.
the same thin applies to going out of the corner, you cant hit full throttle to soon. but try applying throttle slow and smooth, keeps the pack stable and must be done in all classes slow and fast.
When you drive through a wide corner, make it as smooth as possible, don't use more steering throw than needed. Make the turn long apply steering throw gentle, to not upset and unsettle the car.
Generally drive smooth and without doing to much with the car, make it flow as naturally as possible. the car doesn't like being rushed on.
To be consistent you need to drive without mistake, clear enough. But on the way to getting consistent, you also don't want to make to many crashes. Drive the car gently, and make sure you hit the corner in the right angle, speed and in the same line each time. in the start do it slowly, then when you are getting better at doing "the same lap" each time, you can drive faster.
But if you are making many mistakes when you drive, you should slow down your pace. Don't try to hit the apex in each corner, but try being 30 cm form the apex.
If you are hitting the corner markers, you are driving to hard, or trying to get to close.
When you are trying to hard to get a fast lap, you will get slower, because you are pushing the car to hard. Let the car work as god as it can, the car won't turn faster, just because you are going faster into the corner.
And don't over do your part of driving the car, don't make make a lot of adjusting on the wheel through the corner, it will unsettle the car.
Brake, turn, apply throttle. not brake and turn in the same time, then adjust on the turning a bit of throttle more turning less turning and then yank the throttle.
My little started racing RC just over a year ago, and i'm trying to learn him all these things, and i can see every time on the track, that it helps. Because i am telling him what to work on, and what he is doing well.
One of his mistakes is that he is driving to aggressively, but thinks he is going to slow when he relaxes a bit. That's a typically rookie mistake!
Gentleness is very important!
(and practice, practice, practice ,practice
Sorry for the long post, but it's all important to evolve and get consistent