Just lose weight. People are different in terms of where they accumulate fat. In general, for example (although not always) men tend to gain weight around their lower belly, and women tend to gain it around their thighs and buttocks more. To my knowledge, however, there is no proven way to selectively decrease fat in one part of the body or another by particular diets or exercise routines. Just lose weight somehow.
Decrease carbs. As someone who is active and vain myself I am always fighting the love handle battle. I have found the south beach diet to work the best. Basically cut out the carbs and watch what fruit you eat. All of the melons, grapefruit, and oranges have high sugar content. You can eat fruits with berry in the name. Next, you have to do aerobic exercise.
Overall weight loss. With natural weight loss (by eating fewer calories and exercising more to use up stored fat), one loses fat from all body parts. So, it is hard to just lose the "love handles". Doing exercises to strengthen and build up the abdominal muscles can hold the tummy in better, which will improve the appearance of the tummy.