In reply to Rick Graham:
Apply to a clean surface, careful to get it flat, and pre cut to oval edges, it so it doesn't have corners to peel off.
Then rub hard, for ten mins, smoothing it away from Centre of the patch to really get the adhesive well attached to the fibres. This also creates frictional heat which softens the adhesive for a better bond. I suppose a light ironing or hair drying could also help. If you don't care about looks, then a smear of aquasure/seamgrip/shoogoo can make the edges less likely to peel.
Use on inside AND outside of garment.
I've had good lasting results from it, and the same principles apply to any other tape repairs.