I do about 150-200, reps of 15 about 4 normal situps (keep head up don't let it fall on your chin), 4 sideways elbow to opposite knee, 2 reverse and then whatever else i can manage... i'm getting a nice flat tum and i've been doing that for about a month. also you shouldn't do them everyday - i know it;s annoying cos you feel like you'll get a flat tummy quicker but you won't, when you do exercise like sit ups or weights, your muscles tear and when they mend that's when you get the tone (sounds dodgy but it's true) but if you keep tearing them everyday and never let them repair, you'll never see the benefit.