poke the screw through a piece of masking tape with the sticky side of the tape toward the head. Place the screwdriver in the slot, then fold the tape up onto the screwdriver. Once the screw is well started, pull the screwdriver loose and remove the tape.
Grab a compact disc (scratched ones that won’t play work just fine for this) and center it on the hole mark. As you drill the hole, watch the reflection in the CD—keep the bit in a straight line with its reflection for a perpendicular hole every time.