Put a piece of a thick rubber band in the screw hole and then use the screwdriver, pressing down so that the screwdriver engages the screw. This works good on small stripped PH or slat head screws. BEFORE starting, read the following>>
NOTE: You want to be sure to get the screw head and the screwdriver lined up BEFORE inserting the piece of rubber band. I use a very fine line permanent marker on the top edge of the hole where the screw is in order to get the orientation correct. Then mark the piece of rubber the same way. I use narrow, fine tweezers to insert & adjust the piece of rubber to line up with my screw hole marks. A long sewing needle can help you fine tune the alignment. This way, you'll know exactly how to line up your screwdriver head AND avoid chewing up the piece of rubber band. And with a little patience, the screw will come out.