Does your stomach puff out somewhat, despite strict dieting and exercise? Check your standing posture. Stand straight. See if you can keep a book balanced on your head while walking. How do you sit at work? At home at the computer? While watching TV? Don't slump in your chair. Slouching or slumping will accentuate tummy fat. Sit straight and you'll look trimmer.
Good sitting and standing posture will strengthen lower back muscles, and stronger lower back muscles will make you more efficient at performing ab-targeting exercises as well as fat-blasters like deadlifts and barbell squats.
Bad posture can cause back pain, and you don't want that when going into your back squat set or abdominal routines.
In addition to the exercise of practicing good posture, do back extensions. Lie on stomach, forehead to floor. Place arms at sides, palms up. Contract muscles of the back and lift torso off floor. Hold for two seconds, then return to start position. Do 12-20 reps.
Harder variation: while lifting torso off floor, lift legs off floor, but keep them straight.
Hardest variation: place arms straight out in front and lift off floor as you lift the legs off floor.