What are two key things to do to flatten the "stomach" or flabby abdomen?

Answer 1

You can do some stomach crunches and eat a diet of cabs, Protein, a little of natural fats and vegetables. This will help you lose the stomach fat easy. But don't forget to exercise on a regular basis for at least 20 to 30 minutes.

Answer 2

Run and do at least 30 min per day of cardio workout. and do different types of sit-ups and other abdominal exercises.
I.E:

Head Lifts

Lie on your back with your arms at your side. Bend your knees and keep your feet are flat on the floor. Inhale and relax your abdomen. Exhale slowly as you lift your head. Inhale as you lower your head.

Shoulder Lifts

Use the same procedure as the head lifts, only lift both your head and shoulders off the floor. When you are comfortable with this, progress to the curl-ups.

Curl-ups

Use the same procedure as with the shoulder lifts. This time reach your arms as you slowly raise your torso to about a 45 degree angle (halfway between your knees and the floor ). If you prefer you can cross your arms on your chest with your hands on your shoulder or you can place your palms on your ears or behind your head. To prevent injury, never pull forward on your neck. Do up to 25 repetitions.

Abdominal Crunch

These are great for strengthening the abdominal muscles and reducing a protruding stomach. Lie on the floor. Hold your legs at a 90-degree angle with your lower legs parallel to the floor. (You can also place your legs over a bench or a piece of furniture.) With arms at your side (or on shoulders or behind ears as in the curl-ups), inhale slowly as you raise your shoulder off the floor, forcing your chest muscles toward your legs. Pull your hips upward, hold for a second, then exhale slowly and roll down to the starting position. Do up to twenty-five repetitions.

To view the movement of this exercise and others, go to http://www.bodybuilding.com/fun/abs.htm

Reverse Curl

This helps strengthen the lower abdominal muscles and reduce a protruding stomach. Lie on the floor. Bend the knees, place the feet flat on the floor, and place arms at sides. Pull the knees to the chest, raising the hips off the floor; do not let the knees go past the shoulders. Keep your head in a neutral position. Slowly return to starting position. Exhale as you pull your knees toward your chest; inhale as you return to starting position. Repeat until fatigued.

Answer 3

Do crunches and go on a high protein diet

Answer 4

Sit-ups and Crunches.