I wrote a hub on this exact question if you're interested.
The most important thing is cutting calories, so focus on foods that are low in calories BUT high in fiber and protein, since fiber and protein are the nutrients that help you feel full. Eat enough of them and you'll be able to go a lot longer between meals without feeling hungry. Good sources include fat-free Greek yogurt, lean chicken and turkey, apples, oatmeal, brown rice, broccoli, eggs, beans, lentils, low-fat cheese and basically all fruits and veggies. My hub has a huge list of suggested foods.
Add in exercise for faster weight-loss: interval training will help you burn more calories in less time (google 'HIIT workouts' for ideas).