When Dylan said "grip with your knees", what he means is squeeze the bike with your legs. It keeps you in control while in the air. Have you ever heard of the gyro effect? When your jumping certain variables make your bike do different things. You can compensate mid-flight. If your in the air and your front tire is high you can pull the clutch and hit the rear brake. It will bring the tire down. If your front tire is low in the air you can rev the throttle and it will bring it up. Have fun. Start small. Stay safe!!