You could try knees to elbow. Hang from a pullup bar, and try raising yous legs such that your knees touch your elbows. 3 sets 12-15 reps.

It depends on what works for you. I work abs 5 days a week, and that routine works very well for me. I never do the same excercises 2 days in a row though. Just make sure you keep your abs sucked in and tight while doing any ab work.

Oh dude i've been there. I basically rehauled diet and workout regimen. Try doing abs/obliques with weight plates or medicine balls 4 times a week. I'd avoid all pasta, cheese, bread, and any other source of carbs. + Don't kill yourself with cardio, i did cardio 4 times a week (30 mins on the treadm...