Not too many have posted issues on this but I know I have snapped a few in my 28 builds to date!!
The best solution is to avoid the problem in the first place. Using a 2mm drill bit, drill the hole for tuner screw to the appropriate depth, then use the screw started bit from the Guitar Repair Tool Kit pictured below.
If you choose to ignore this and break the screw in the hole you have little option but to use the screw extractor (pictured below) and then plug the hole, repaint and start again with that hole.