If you're going off the road go straight off. Don't try to save it. Turning in too early. This happens because you think you're going to get through the corner faster because if you turn in early you're not turning in as tight, but by doing this you wind up sliding through the apex to turn out. Entering the slower corners too damn fast, then scrubbing off speed as you squeal all the way through the turn.
Most new drivers are too fast into the slow corners, but too slow through the faster ones.
Don't be braking while turning in. It's best to brake too early then be back on a constant throttle well before turn in. Then on later laps you can slowly move up the braking zone closer to the turn in. This is especially good for the faster corners. When you get almost to the apex look for the turn out point.