sharla, this is a great ex to learn proper hook and uppercut form. it's also good for strenght training.

take a large leather medicine ball, about 8-10lb, and tuck it in your arm like a football. now do uppercuts. a true upper motion will let the ball just slide across your body but the angle in your arm will not let it fall out. you can "catch" the ball at the end/top of the motion so that it doesn't go flying out of your arm. when you do this, really get your legs and body involved and rotate upwards and to the side while really pushing off your back foot. your trunk is where so much power comes from. you should start out almost facing east and down and ending up facing north and upright.

doin the same thing with the left hook will also help your form. but you'll find this one is much more difficult, which supports the notion that most people's left hook sucks. note that this is a palm in left hook, but for short left hooks you can do the same motion while turning your palm down en route to your opponent's chin, which in turn, brings the elbow up. maybe I'll make a little vid.