TIP 1: DON'T PUT HOLES IN THE ROOF
In the movie National Lampoon's Christmas Vacation you may recall Clark Griswold putting up his lights with his trusty staple gun.
Please don't do that!
TIP 2: PLASTIC CLIPS ARE YOUR FRIEND
Instead, use plastic clips. There are a variety of clips that let you hang Christmas lights without causing damage to your roof by clipping onto the gutters, shingles or eaves.