Most of this has already been said in one way or another but:
1) Water - free way to be "full," don't mistake thirst for hunger
2) Protein - slow digesting
3) Fiber - slow digesting
4) Don't eat when you're not hungry. Duh. Understand the difference between an emptying stomach and real, legitimate hunger.
5) When you're hungry, eat a MEAL, don't snack. Sit down at a table and eat a real meal. Eat with a purpose. Eat several times a day, with meals built around lean protein and surrounded by vegetables, whole grains and complex carbs, and healthy fats. Water, before, during, and after the meal.
6) Stay strict during the week and indulge on the weekend, WITHIN REASON (e.g. a piece or 2 of cake, not the whole fvcking cake

)
7) Maintain physical activity. If you don't move around much, you're going to have problems regardless of your diet -- unless you can watch your food intake fanatically for the rest of your life, which is hell in and of itself. Ways to stay active include: get a physical job, find excuses to walk A LOT (to work, to shop, to friend's house, etc.), get involved in fun physical activities/sports, etc. If it is something you just do as part of your life, rather than a chore you
have to do (like 32.342934 min on a machine at level 5 intensity every other day burning 304.76824 cal -- YAWN), your chances of sticking with it are much better IMO.