I have a Hangar-9 J-3 and several other tail draggers. Flyboy Dave is absolutely correct. Do the wheels the way he says and your takeoffs will be much better. Also, do remember that there is generally no need for full power on takeoff. So come in slowly with the power keeping the plane lined up with the runway. Then lift off at a shallow climb angle until you have a good flying speed. Then keep the power coming in toward half to full power for the climb. This procedure will prevent wing tip stalls followed by the subsequent cart wheel on takeoff.