Use the correct screwdriver bit or driver size
Apply firm downward pressure while turning slowly
Tap the screwdriver into the screw head to seat it better
Place a rubber band between the screw and driver for extra grip
Use a manual impact driver
Try locking pliers if part of the screw head is exposed
Cut a new slot in the screw head with a rotary tool or hacksaw
Use a screw extractor bit
Drill a small pilot hole and use a left-hand drill bit
Apply penetrating oil and wait before trying again
Heat the screw if thread locker or corrosion is present
Remove surrounding material if needed to expose more of the head
Replace the screw after removal