Dude, just limit yourself to weekends. If you just vaguely say "Only for a little bit" or if you keep saying "Only for 30 minutes" or "Only for this round" you're going to be making planned short sessions into long one. So just bust your ass during the Weekday with schoolwork/jobs and then when it's Friday and Saturday game on till your eyes bleed. Sunday, you have to exercise some self-control and judge if you have any stuff to do.
Edit: But cutting gaming all together won't help either. Video games are just as valid form of escapism and relaxtion as any other thing. Addiction, dependency, and obsession are bad with anything. Jocks get bad grades by practicing/excerising too much, Bibliophiles will get out of shape and may not do their school work, etc. There's no good addiction, a dependency is always a weakness. Just make sure you can get by without something. Until you get to that point, have firm, clear, and easy to follow limitations. Weekend plan is the best, because there's no way you'll get around that.
