well the way i learned my whips it sucked learning double whips... my first whips were all feet.. so i didnt know how to use my wrists... just practice standing on the ground and whipping your scooter around with your wrists only, then when you hit a jump or go off a ledge kick the deck around with your feet and the second rotation is all wrists. just practice the motion, and yea its just a bunch of practice to get them consistently.
if you find that you keep landing befor the double whip comes around jump really high and tuck ur legs into ur chest then when the deck coms around slam them on... then when you start getin better at them, start catchin them.. wayyy more stylish