So this is going to be real quick and dirty. I am pretty sure we have all tried the gimmick diets that work for a little bit. But after awhile, you gain all the weight back. So after about 18 months of losing weight, I have found what works:
Calories. It's all about the calories. I keep mine below 1500. Doesn't matter what I eat, as long as my calorie count stays below that. This means I CAN have that doughtnut, or slice of pizza, or ice cream cone. I just make sure I count those calories into my total for the day and make adjustements.
Cardio. I do at least an hour of cardio 5 days a week. This way I burn an extra 700-800 calories a day.
Now, this works for me because I have a LOT of fat to burn, and I am a guy, so I can naturally burn off more. This won't work for everyone.
And...this is just to lose the fat. Once I am down to my goal weight, I am going to switch to weight lifting, which means I can consume more calories. My diet will then adjust.