Advice from a novice who installed the decals. Clean the area thoroughly with alcohol first. Line up the decals before removing the backer to ensure proper orientation, fit, etc. It can be helpful if you use painters tape for a guide to where the edges should be when applying.
Peel off one end of the backer, align the decal and put it on starting from one end to the other, smoothing it along the way (don't get air trapped in there) and peeling the backer as you go. Use a smooth piece of plastic, (some use credit cards) and rub over the decal to make sure every part adheres. Especially on the small pieces and edges. Carefully peel off the front film, making sure the decals stay attached to the bike. If you see they aren't, let the film back down over that part, rub some more, and continue peeling.
I forget the temp but you shouldn't apply them if it is colder than 50F (I could be off on that).
