The "Rule of Thumb" is: if whatever you do doesn't work - do something different.
For instance, let's suppose that you tried counting and reducing calories and failed. Try counting and reducing carbohydrates instead. Failed again? Try counting and reducing fats. Try watching portions, try eating more meals daily but small ones, try going for fruit or even complete water fasts weekly.
If you don't do strength training - start doing it. If you do the weights but all the same for a long time - change the exercises.
If you, walk or jog or do any other cardio exercise for too long at the same pace, start increasing intensity and duration of it, or start swimming or hiking.
If you never paid attention to so called "calorie density" of your meals, try learning how to work with this very handy weight loss tool. The matter is, if you eat 200 Calories in the form of, say, white bread, you'll became hungry again sooner than if you ate same 200 calories as a bowl of salad with olive oil.
Practically speaking, fibery, bulky foods satisfy your hunger with fewer calories. So go for vegetables - raw, in soups, is salads, as main dishes, etc.
Best of all, try doing several things that are NEW for you simultaneously.
