my own personal policy towards quitting is very simple. don't do it, just make weed a reward. did you work hard today and finish all of your homework? smoke. smoke as much as you'd like, you're all set for tommorow. didn't do your homework yet? get working or else there will be no time to enjoy the high. also, you get a great feeling of accomplishment which always makes my highs a LOT better.

try it out, all you really need is the willpower to say "no smoking, i didn't get done what i needed to get done"