Come into jump with legs about shoulder width apart. Throw the spin with your uppper body (arms, chest, head) as you pop off the lip. (Be sure and pop, don't suck it up. Also, don't take off early.) For a big spin, I'll use the inside edge of my right ski (when spinning left) to set my rotation. From there, just keep your head in the spin till you can spot your landing. If you pull things in tight, you'll spin faster. However, be sure and look at the horizon and not down so you don't go off-axis.