OK, let me ask a really stupid embarrassing newbie question: during acceleration, when should I change the gear? When the little red light comes on, or when the the RPM needle enters the red zone?
Red light usually indicates the best shifting point, but most of time when I drift, I always shift near to the cutoff. Shift so you feel that the car has power, don't shift too late or too early
Shift up when the red light comes on. Going up a steep hill, leave it a fraction longer.
You should shift down when shifting down no longer causes the wheels to lock. On a lot of corners this means shifting down to the neccesary gear for the corner (for example 4th straight down to 2nd) as soon as you start braking, if not slightly before.