Achieving fitness goals has more to do with the kitchen than the gym. As a general rule, you'll want to eat about 12 calories per pound of body weight if you're cutting. You'll want your caloric breakdown to be 40% carbs, 40% protein, and 20% fat. This is a general rule, so tweak these numbers as they fit your body. Ideally, you want your carbs to be complex, your protein to be lean, and your fats to be non-saturated.
At the gym, find a program that keeps your interest. Higher rep ranges do not make you leaner. Muscles get bigger and smaller... not leaner. You should generally work in a 6 - 12 rep range, depending on what exercise you're doing. Dedicate more time to the larger muscle groups; legs, chest, back, and less time to the smaller muscle groups; biceps, triceps, shoulders. As Agalloch pointed out, seeing your abs is all about body fat percentage. That said, don't treat you abs special. They are a muscle, which means you should hit them once a week, using resistance.