Centered screws depend on a good start
Many times when using an awl or a nail to mark a position for drilling a pilot hole, heavy grain in the wood causes the awl to veer off the desired centerpoint. You can avoid this problem by using a 1/32" nail set and a small hammer to mark the hole locations. The concave tip of the nail set helps keep it aligned regardless of the wood's grain, making it easier to get the tip of the drill bit exactly the in right spot.
-- Thomas Peter, Midland, Mich.