hey dude im a ski instructor so i kinda hope this helps=P but try going for a J- turn so when you are going down a hill, turn until you are going almost uphill. then once you havee those down, start sliding into them more by releasing some of the pressure on your edges. LEAN YOUR KNEES UPHILL!!!!!!! but not too much, just enough so that you have that edge pressure.
if that doesnt work, try this:
stand sideways on the hill ( your hips perpindicular to the "fall line") and slowly release your edge pressure so you start sliding. do that for a few meters, then put pressure back on your edges and stop yourself. it might feel wierd at first, but it does help. then start doing that into your turns and eventually you will be able to stop successfully! but most importantly, PRACTICE MAKES PERFECT=D i am glad to see another snowboarder join the epicness of freeskiing!