Well I have put window stickers on many a time and I just clean with windex very well. Then start on one end stick it down and use something flat but kinda solid to press it down. Go over the whole sticker a few times till your sure its on good and most of it should be good. Sometimes you just get a few bubbles but you can take a pin and pop the major ones, the small ones usually come out after it sits a few days in the sun. The heat takes the air out of them and it will sit flat.