Stay off the brakes as the brake pedal behaves like a handbrake. The slightest steering while braking for a corner will send you into a permanent snap spin. Lift off the gas to start the auto-braking feature and your car will slow down sufficiently for almost every corner in the game.
When you get into trouble after entering a corner too fast, press PIT SPEED LIMITER to instantly slow to 75 mph without crashing. Turn it off again right away.
The down-force settings and gear ratios will affect your straight-line speed and must be adjusted appropriately. Most of the other options have minimal effect.
Even with the Rules Enforcement option turned on you can use shortcuts at many of the chicanes at most tracks. You will have to determine how far off the track your car can go without incurring a "shortcut" penalty by trial and error.