Hmm... kind of a loaded question...
I touched upon this at rennlist-
http://forums.rennlist.com/rennforum...ds-help-2.html
But the issue isn't even as simple as keeping momentum up.
As a driver's experience progresses, car setup changes. A beginner will probably prefer a tighter car- one that pushes. That way the worst possible thing he can do is just push off the track if he holds the throttle too long. As the driver gets better with actually controlling the car, the setup will get looser, and become more pointy. How the car is driven changes.
In general, as the movie quote goes, loose is fast. But just because loose is fast doesn't mean everyone can drive such a setup. A tight car won't want to "dance" but a loose car will quickly tell you you're not in charge if you're not on top of it.
If you're really intent of improving as a driver, making setup changes throughout the day will really help you understand chassis dynamics. Get outside your comfort zone, but don't drive beyond your ability. In general, when I see someone off the track or looping it, I think- driving beyond ability.
EDIT-
I attached a pic of me at Road America, T5. You can see the cone on the gator strip, and my tires within 3 feet (probably less) of that edge. In addition, you can see by the way my car's weight is jacked to the rear right corner that I am accelerating through the corner- all braking finished way beforehand. That is what they mean when they say "slow in, fast out."