No real tips - they should come off pretty easy. Once you get an edge, though, go sloooowwww. It will make you pay a penalty if you get anxious and the second you try to go for speed, the number will tear and explode into tiny strips. If you are patient and go slow, it should come up in big pieces. Also go super slow at the very last bit or it leaves a tiny tip.

Once removed, if you have any adhesive left behind on the sail, use goo-gone or denatured alcohol to remove the remaining tacky spots.