When working out my abs should I do a daily routine or or work them one day take a break the next, then work them again?

It is ok to work your abs every day. They are one of just a couple muscle groups that don't need to be rested 48 hours after a workout.

I'm also trying to work my abs. I want to do the equivalent of 150 sit ups a day, but I know that it's important to work all the ab muscles and normal crunches don't do that. I would like to know how I can divide this into different exercises (maybe three sets) to work different ab muscles. If anyone could help, that would be great. Thanks.

David...If you aren't already doing this...try going from right to left and visa versa, while doing your crunches. Also, try scooting up to a wall so that you can place your feet on the wall, about 2 feet off the floor. Now do your crunches in that position.

A good one for the lower abdominals is to lay (on your back) on a bench, with the lower half of your body (from the butt, down) off the end of bench, so that your feet can hit the floor. Now extend your legs and slowly raise them up, just short of a 90 degree angle. Lower back down slowly, until your feet are about 6 inches from the floor. Repeat this exercise until it hurts. Rest and do another set. Rest and try a third set.