I clean the area really well with acetone, then let it dry. Then before applying the sticker, I spray the area with some water with a few drops of Dawn dish soap in it. Peel the backing off the sticker and apply it. The surface being somewhat wet, will allow you to move it around until you get it exactly where you want it. Then take a credit card or some such thing and smooth it over the sticker. That will squeeze out a lot of the soapy water and should eliminate air bubbles. If you see bubbles, just keep using the card until you get rid of them. Let it dry over night, then peel the paper off the front of the sticker.
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