Can't seem to get any 'snap' into my punches...

Do you have access to a trainer who's good with beginners? If so, have him deconstruct your hook and build it from the ground up. The hook is a whipping punch usually. You bring the punch through AFTER your body finishes rotating.

Best advice I can give is to learn to throw a discus (I only did it for one season in high school and it's easy/fun to learn). The mechanics of a hook will make total sense to you then, even though it's the opposite arm. A lot of the power comes from "stopping" your right side, which makes the hooking arm whip around harder. Also get your hip into the punch, and the best way to learn that is to practice a Mexican liver shot. This dude has the power principles down if you're a visual learner: http://www.youtube.com/watch?v=0-NAKBQfwkE

Main thing with a hook is it's a really violent punch and you sort of have to lose control of your arm and let it do its own thing. It's not a strength punch like the right hand can be, it's a whip with a weight on the end of it.