Five small meals is good advice. Try and eat some protein in each meal, this could include stuff like nuts, yogurt and tofu besides the obvious chicken and fish. I always eat bigger portions than I really need, one trick that helps with this is to drink a full glass of water before you start eating. That fills your stomach a bit so you can be a bit more restrained.
If there are snacks that you just can't do without, try to find the least bad option in that snack category. Homemade popcorn with just a little butter and salt is a lot better than chips or nachos (or disgusting microwave popcorn), for example.