On a frontside spin, your front will be facing down the hill after the first 90. On a backside spin, your back will be facing down the hill after the first 90. For slides it depends on which part of your body is facing the rail when you ollie on. Front board = front facing rail, back faces downhill after you jump on. Back board = back faces rail, front faces downhill after you jump on. It can be sort of confusing at first I guess.