The key is to keep the sail furling without any creases. Although tensioning the outhoul seems to help , it is best to keep the boom position so that a very small tension applied to the outhoul keeps the sail so that it furls without any creases.
Try to find the best position to your boom first and you will see that the sail will properly rotate on the drum. The applied wind tension will be enough to keep the sail in correct position. If you do not have any wind (moving your boat will create enough wind for the sail) apply minimum tension to outhaul. A single turn around the winch will be generally enough.