Baby oil or any other mineral oil, and a credit card, and of course, a whole lotta time lol. I start by taping one side, smoothing on some oil all over (pain in the butt if you have animals, because then you gotta be extra careful not to get pet hair in there) sticking it on there, flatening it with the credit card, then taping the remaining edges when I feel ive gotten out all the bubbles to the best of my ability. And you will never get them ALLLLL out. Most but doubtfully all unless you are a heck of alot more persistant then I. 