it depends on how much excess skin you have that needs to be tightened up
a pic might help (no homo)
there is nothing that is going to make your skin tighten up any faster then what its going to, the best thing to do is cardio (i know it sucks) but thats the best way to tighten everything up besides surgery, and built in with your cardio is weight training you should do something more intense as in no rest or very minimal rest inbetween sets, and different excercises.
i know there is skin tightening lotion that ive heard of women using after a pregnancy to help tighten up the skin around their bellys, but idk if that works or not