I do ok with the fixed windows. As far as back windows (or other curved ones) goes, when cutting to size on the outside of the window use a heat gun, or blow dryer, to take the wrinkles out of the tint and hug the window real nice then when put on the inside it takes the curves and sits flat on the glass. Now as for the roll down windows, ahhhh that I have not been able to do perfect, mind u I have only done 2-3 tint jobs ;-)on my own vehicles, not a lot of practice. I figure next time I do tint, if I do, I might look into removing the windows apply the tint then reinstall the windows, As much as I like to do DIY I will prolly just save money and get it done tho lmao lol