You should start every abs workout with a little cardio. Cardio raises your heartbeat and engages your abdominal muscles. Try 5 minutes of jogging, jumping jacks, high knees, or a variety of all 3.
This is a great exercise for the lower abs. Lie on your back with your legs straightened in front of you about 6 inches off the ground. Slowly raise both legs up and drop them down as low as you can. Focus on your keeping your lower back on the ground. If it starts to come up don't bring your legs as low down.
Stay in the same position as leg raises, but bring your legs up about 90 degrees. Slowly move both legs in a circular motion clockwise, then counterclockwise. The bigger circles you make, the more you can feel it in your lower abs.
Lie on your back with your legs bent at the knees. Straighten your legs out about 6 inches off the ground then bring them back into your chest. That's one crunch, repeat.
Stay in the same position with your legs straightened 6 inches off the ground. Bring one leg up about 45 degrees while the other leg moves down. The lower you flutter your legs the more you will feel it in your lower abs. But again, watch that your back doesn't come off the ground.
This is a great exercise because it works the whole muffin top trouble area; obliques, love handles, and lower abs. Lie on your back with you knees bent, feet flat on the ground. Bring your shoulders and arms a few inches off the ground. Using your core swivel from side to side, like you are touching your heels with your hands. Unless you have very long arms you probably will not be able to actually touch your heels.
Lie on your back with your legs straight and your arms above your head. In the same motion, bring your legs up 45 degrees and your arms over your head like you're going to touch your toes. Your body will form a "V" with your butt as the point.
Lie on your back with your legs straight in the air, about 90 degrees. Put your arms at your side to help balance. Using your core, bring your back off the ground while keeping your legs at 90 degrees. Bring it back down and repeat. It's okay if aren't flexible enough to keep your legs straight, just keep them as straight as you can.
In the same form as the pulse-ups, lie on your back with your legs straight, perpendicular to the floor. Bring your arms up so they are also perpendicular to the floor. Then raise your upper body up towards your toes. Make sure to raise with your core and not your shoulders. Again, it is okay if you cannot touch your toes.
This exercise works your obliques. Balance on your butt with your legs bent at the knees. You can cross your ankles if you do not feel well balanced. Twist you core from side to side, still balancing on your butt. If you want to make this harder you can hold a medicine ball or weight.
Get in a push up position, body straight, balancing on your hands and the balls of your feet. Hold this position for 30 to 60 seconds. Try to keep your body in a line; do not raise your butt up or drop it down.
Lie on your right side with your legs straight. Prop yourself up on your elbow and reach your left arm towards the ceiling. Hold this position for 30 to 60 seconds. Repeat on the left side.