When working out focus on a muscle group and dominate it. Run your muscle to complete exhaustion then do ten more. After this you need to move on to another muscle group. Try and focus on two a day or if you are super disciplined you can do it three times a week. This will only work if you hammer your muscles hard and then you will have to do more than 2 muscle groups at a time.
I work out everyday starting with my arms and chest with some abdominal work then on day two I do my back, legs and more abdominal.
You can work your abs everyday, the never really need to rest, especially if you are working on making them look like a wash board. If you do not see a difference after about 2 weeks then you need to do more and longer.
Increase your weights and do less reps this will help you build muscle more rapidly. If you want long lean muscle do more reps with slightly less weight.
The key is to keep changing your work out styles not the muscle groups. Your body will become used to the routine in as little as two weeks.
Challenge yourself and work hard these goals are obtainable.