[Simon Meisinger]

Those are total basics, so excuse me if you're already familiar with them and seek more advanced tipps, but they sure helped me when I started sim racing:

Brakes are (not) for stopping: https://www.youtube.com/watch?v=zXPSj56lavE
Weight Transfer, it influences everything: https://www.youtube.com/watch?v=ZX4euX-1rug

And another thing I had to learn and didn't know by nature: let go off the brakes slowly when you're done slowing down the car for a corner, just releasing them in a sudden move upsets the suspension and generates instability (sudden weight change).