PBO Reader Phil sent in this tip.

Prevent crossed  and stripped threads, especially when refixing screws in GRP. (And plastic tops on French milk bottles!)

Ensure threads are clean and offer up the screw, bolt or nut by hand; turn it anticlockwise until you feel it ‘drop’ into the correct groove.  Then turn it clockwise with your fingers.  If it doesn’t turn easily be very cautious before applying the screwdriver or spanner.