The simple mathematic goal is calories out > calories in. Some useful tips:

Eat SOMETHING, ANYTHING within 30 minutes of waking up. Fruit, oats, eggs, are good examples.
The last thing you eat should be at least 2 hours prior to going to sleep.
Drink a LOT of water.
Get your recommended 20g of fiber every day.
Eat a minimum of 3 servings EACH of vegetables and fruits.
Do not drink soda or caloric beverages (exceptions might be 100% organic juice, such as grape or cranberry).
Do not consume high fructose corn syrup.
Do not consume trans-fat or hydrogenated oils.

If you follow those rules the more general rules that people will give you will kick in automatically:

-You will be able to easily manage your portions.
-Your blood sugar will remain level and discourage gaining fat.
-Many of the foods you eat within the parameters I mentioned act proactively within your body to burn the fat (antioxidants, etc).