Lots of veggies- plenty of vitamins and low calories. Sweet potatoes have a lot of nutrition in them. Apples are recommended for fiber and are an excellent energy source, releasing sugars more slowly than many kinds of fruit (see private message).
Good fats found in pistachios, almonds and walnuts as well as the protein they provide make these nuts good ones to eat. A suggestion I once heard was to eat a small handful of nuts prior to having your meal to help curb your appetite.
Another one I saw recently suggested a glass of water with lemon in it- don't remember if it was a half hour?- before your meal can help you feel less hungry.
Losing weight fast is not a good thing to do- slow weight loss is the type of weight loss most likely to be maintained.
Real food, not prepackaged. Visit the produce department and look for colorful foods. Eat a big variety. Try vegetables on the grill. Try turkey chili with lots of veggies added.