Cut out the sugar, limit the fat, avoid carbs or eat them only a few times a week (prefer whole cereals instead of the refined ones that are just quick sugars, great to make you crave for more), drink plenty of water, eat vegetables and proteins. Read the labels, to make sure you know what's inside you're buying. You also need to tone yourself up, and if you want to get rid of your cellulite (if you have some), apparently what's best is to use specific creams, and combine with exercise to make sure you evacuate it. Vegetable are pretty much very low calorie, so don't hesitate to eat a full green plate rather than fall for carbs. You need to protein, no matter what you prefer, because they are your muscle and participate in creating the keratin of your hair. Not enough protein, and it's your muscles that will be lost, not your extra fat/water.
You can have little snacks if you're hungry, you can take a yogurt and a few nuts or almonds, or a protein bar.
Be patient, if you loose a lot of weight in a short amount of time, or if you starve yourself, your body will think it's war outside, and then even the smallest drop of water will be stocked, and that's how you gain back everything you lost and even more.