Recovery from understeer is easy, get off the gas and wait until the tires hook up. You don't even need to totally release the pressure on the gas pedal, just stop trying to go faster, you can't. Once you slow enough for the tires to hook up you will be able to steer and you can try feeding in a little more throttle.
Oversteer is more of a challenge for most of us. You must steer where the rear tires are trying to go while also backing off the throttle a little. When the back end starts to hook up it will want to swing the other direction. You must steer to counteract this until it is following the front wheels again. If you do not do it right, you will swing from side to side until you scrub off enough speed. If you really mess up you will spin.
In both situations, you do not want to make any abrupt movement of anything. Steering wheel and brakes all must be used gently. Your car is trying to go out of control and abrupt movements will help it do that. Your changes must be gentle but not overly cautious. Oversteer is the trickiest by far for me. It is also the most fun to practice.
Safest way to practice outside of a school is a parking lot with snow. Turn of the stability control and try a few. Watch out for light poles.
128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport
Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09