Extreme diets usually don't work. They usually call for extreme measures that most normal people can't stick to due to lack of willpower, lack of time, lack of patience etc....and a lot of people end up binging once they've reached their goals and ruining the whole thing.
You should try to just limit yourself - instead of buying the box of oreos, buy the small pack of 6 (this way you can make sure you won't eat the whole box). Eventually, you might work down from there to getting no oreos.
Drinks have a LOT of calories. I'm not saying your an alcoholic but if you can't just cut that out, you might need to go to AA meetings or something.
I know people who have lost a lot of weight on wieght watchers. You might want to try that because it allows you to eat whatever you want within "point limits". However, I believe there is a monthly cost so unless you're really serious about losing weight, don't do it.
Also...you could try getting a nutritionist and/or a trainer. A trainer will help you set goals for yourself and teach you certain excersizes to do to reach your goals faster...but since they're expensive, you might want to just get one once or twice to teach you the basics.
A nutritionist will evaluate what you eat and tell you how you should change your diet to reach your goals.
Drink water when you are hungry, like TheKak said...but if you just feel like munching on stuff a lot, it might be good to get baby carrots, celery, etc instead of chips. I believe carrots and celery are some of those "negative calorie foods", but if not, they can't have too many and they're healthier than chips. For other options, I sometimes suck on/munch on ice cubes or gum to stop myself from eating crap.
Don't keep too much yummy junk food in the house. I find it really hard to resist it when it's there. The best thing to do is just force yourself to avoid buying it and once you're at home, you won't have it there to eat.
If you join a gym, make sure it's close to you. I used to be part of this gym really far away from my house and I hardly ever went because it was just such a pain in the ass to go over there. Ever since I joined a gym across the street from my house, I've been going every day/every other day and I've seen a lot more improvements.
If you like any sports (like Tennis), try to do that more often...and don't stop when you break a sweat. Do it until you're dripping sweat.
Oh yeah...and a lot of people will say "it's okay to designate one day to eat whatever yuo want but just don't go overboard". I think that's a great way to mantain a diet. If you eat super-healthy all week, it's okay to reward yourself with some candy or a nice juicy cheeseburger at the end of the week. Just don't eat a quart of ice cream as a reward
