What's an effective way for me to lose my belly fat?

Diet and exercise: Only treatment that works is diet and exercise. Eat less then you burn off. 3500 calories to the pound. Will reduce your risk of diabetes, high bp, heart disease, cholesterol, infertility, etc. Direct exercise towards your abdominal muscles to firm them up.

Fat: There is no such thing as spot fat loss. You would need to lose weight in general & a certain proportion of that will be abdominal fat. This can be done by eating healthfully, being physically active and making sure that calories burned exceed calories consumed. However you can improve your appearance by toning your abs. To tighten your abdominal muscles consider doing crunches, reverse crunches.

Caloric restriction.: Diet and low caloric intake daily followed by exercise are the only safe ways to accomplish your goal. Your life expectancy will increase once you are successful.