Always keep your hands at 9 and 3
Forget 10 and 2. FORGET IT. Luckily in most driver's ed classes today, teens are taught 9 and 3 because 10 and 2 is just downright dangerous if you've got an airbag. (If you're not familiar with the concept of airbag degloving, click here, or here, if you're not squeamish.)
9 and 3 is also better because if you momentarily lose control, the second you get the car going the right way again, you want the steering wheel pointed straight ahead. With your hands at 9 and 3, all you have to do is bring them back to their resting position.
Brake with your left foot
I've mentioned this one before, but it certainly bears repeating. Many of the world's best race-car drivers brake with their left. On an automatic, you can use it 100% of the time, and on a manual, you can use it whenever you don't need to shift. By keeping your left foot hovering above the brake pedal (not on it, unless you want your brake lights on all day, which is obnoxious), you're seriously reducing the time it takes to start slowing down in an emergency. At highway speeds, that can mean stopping 50ft earlier for the average driver. Thats... a lot.