Start doing a lot of cardio exercises; in fact make it a habit. Cardio exercises like jogging, biking, or even just brisk walking is a great way to trim your wayward tummy. By doing these exercises everyday not only will you lose tummy fat, you'll also slim down your whole body.
Build up your muscle mass. Melting all the excess flab away is not enough; if you don't want them to return then you should build up muscle to help you burn more calories. Do some strength training at the gym, this will both melt away the fat and give your muscle that sexy, toned look.