I had a friend(yes, it's hard to believe) that used to tint windows for a living. He made all of the cuts on the outside of the vehicle and then used the pieces to tint the inside. He used a ever so slightly soapy water to adhere the tint to the window. It also gave him enough time to move it around a little. Rear windows with contours, he used a heat gun to form the tint. Very tricky to keep from overheating the tint.
I have a 4" tall tint strip on my windshield. It is low enough to block out the glare of the sun so that I never have to use those worthless visors. I used 35% tint for that strip. A cassette tape case works wonderfully for tracing the contour of the windshield.