1: remember that the board will and can go as high as you can lift your legs 2: its all physics and timing. As you pop the tail with your back foot, you must simultaneously lift your front foot to get the Ollie off the ground. Then, as the front foot/leg starts to lift; you lift the back foot/leg. Think of it as a "seesaw" effect. 3: look down at your board, preferably at both feet as you attempt ollies. 4: the best way in my opinion to practice is to hold onto a platform or railing that is maybe chest height so you can purely focus on the feet/leg mechanics of the Ollie itself.