First, choose a ratchet strap that is long enough to reach the entire kayak. You don't want it to be too tight, but you also don't want it to be too loose. Next, attach the ratchet strap to the front and rear of the kayak. If possible, try to avoid attaching it directly to the handles or other areas that might rub against the kayak's hull. Finally, use a gentle ratcheting motion when tightening the strap. You don't want to damage the kayak or the ratchet strap by over-tightening.