Dont forget to work the whole of your core. (front, back and sides)
If you just work your abs, you'll get muscle imbalence and prob suffer from a bad back within a few months.
What ever long you train your abs, train your sides(obliques) and back(spine erectors) the same.
For back try laying on your front (prone) with your feet under a weight, or bar and put your hands up by your head. lift your shoulders off the floor and reach up as high as you can go.
notes: keep your head inline with your back, dont tilt it backwards.
the further you reach above your head with your hands, the harder it will get.
try doing it with a twist, rotate your shoulders as you come up.
dont "lay down" between every rep, keep your shoulders an inch from the floor between reps.
For sides, Lay on you side. raise yourself up on to your elbow, using your forarm for support. rest one foot on top of the other. whan you lift up the only thing touching the floor is your hand, forearm and elbow and side of bottom foot. lift up and bridge, hold it for 2 seconds then lower your hips to 1inch off the ground.
notes: hold a weight (large bottle of watter, brick, etc... with your spare arm supported by your hip.
put your foot on a small step, or books for an extra strech.
for abs, lay on your back with your hands above your head holding a heavy weight, or door frame. lift your legs up in the air keeping them together and out strate. take them up and down. find the range of most resistance, the higher you go the easyer it will be.
Make it hard for yourself. Try to find ways to make it harder. You dont want to do more than 20 in one go. try to make it so you can do 15-20 five times each.
Hope that helped.
