edging to keep speed under control you want a rocking motion from nose to tail. aggressively pushing the nose down to go into the turn, then thru the turn your weight shifts back some, repeat. board has to have sufficient effective, sharp edge to really do this right. search riding+steeps+snowboard on utube
i look to the runout zone if there is one, or the gap in the trees of your choosing. it's good to know well the terrain already, 90% mental and visual, you bomb or make the fewest number of turns. i'm usually looking to make a huge heelside turn with weight to the back to dust off some of the speed coming out of the chute. was working this season on toeside dustoffs with a few horrendous, launching heel catches, haah, that was exciting!
practice, mental focus, LOOKING where you want to go, proper equipment...in that order IMLE