Pay attention to your Protien-Carb-Fat numbers in the meals you eat. Every meal should contain these 3 things, in a good ratio. When I noticed the concept of the way my nutritionist was planning my meals, I found this website and it helped explain so I could do it on my own.
http://exercise.about.com/cs/nutrition/a/protein_2.htm
I also learned the same things at a wellness camp I attended last year.
Its really all about eating the right proportions of pro-car-fat in each meal, and eating smaller and often. Feeding your body makes you burn more calories. You also HAVE to exercise. You have to burn more calories than you eat, but you cant starve yourself. Starvation = weight gain.