Watch what you eating 80% of the time, and let yourself have a treat and relax 20% of the time.
Try healthy Monday to Friday then let your hair down at the weekend. This does not, however, mean that you should pig out at the weekend, it just means to give yourself a treat, a reward for doing so well in the week.
NEVER deprive yourself, if want something, have it, just a little bit of it.
If you find yourself having cravings often try drinking a glass of water in one go, this usually helps unless you genuinely are hungry. This is also a good tip if you are giving up smoking and are still craving cigarettes, just drink a pint of water. Not only does this kill your cravings but it is great for your skin and keeps you hydrated.