Use the correct screwdriver or bit first
Apply firm downward pressure
Tap the screwdriver lightly with a hammer
Add penetrating oil and wait
Use a rubber band between the screw and driver
Try locking pliers if the head is exposed
Cut a new slot with a rotary tool
Use a screw extractor
Drill a small pilot hole in the center
Use a left-hand drill bit
Heat the screw if appropriate
Grip the head with pliers after exposing it
Remove surrounding material if needed
Replace the screw after removal