If you freeride you should move the ankle strap higher up on the frame of the binding for more support. If freestyle is your style of riding then move the ankle strap lower on the binding frame for more flexibility. The toe and ankle strap should fit snuggly around your foot. You can lengthen or shorten the straps until they are snug, but not overly tight, over your foot. Lastly, adjust your forward-lean by adjusting your highback.
Most bindings have a forward-lean adjustment on the highback.
The amount of forward lean you choose to ride with is your personal preference. The more forward lean you ride with the more pressure you will be able to apply to your board s heelside edge, and it will be easier to tip your board on its heelside edge. After you adjust your forward-lean, position the highback so that there is no gap between the highback and the heelcup of the binding. Most step-in adjustment is done on the boot. With step-in boots you have to rely on tight lacing to help keep your fore foot down.