Next time you go to install those screws, rub some bee's wax or paraffin, or bar soap or... on the threads before you screw it in and you'll be less likely to strip the head out.
My favorite is lip balm (chapstick). Easy no mess storage and easy to apply to the screw but people use all kinds of stuff.
I predrill the holes for them, using a drill bit gauge card, the hole is just big enough the valleys between threads touch wood.
Coating the screws and predrilling are great ideas. I had same problem even after doing the before mentioned steps, I went to my local hardware store and bought good quality replacement screws. Economy priced hardware like tuners bolts and neck bolts are often very cheap and will snap off if you look at them wrong.Haha
Phil, I have always used a 1/16" drill bit to make pilot holes, rubbed the screws through a soft was bar, and screwed in the probably less-than-average screws that come with the tuners. No failures over 50 git builds. Pilot holes and lube are vital, as cheap screws driving in to hardwood is a sure fail, sooner than later.
I have a old grader I use and a bar of soap. I grade it into the box like parmesan cheese and shake it up.