I tinted for a few years. We used llumar brand film. Several levels in it. Use a metalized film, it resists fading and color shift best. It's more expensive, but worth it.
As mentioned, use Johnson's baby shampoo. couple ounces per gallon of water.
You'll need a couple squeegies and a razor blade.
1- roll window down about 1". on the OUTSIDE of the window, wet the glass. put the tint on it, backing out, along the seal edge. film against the glass, squeeze out water. Cut the film along the top edge of the glass, then sides.spray the outside of windshield, take the film off and put on the windshield while you work.
2- roll window up, push the seal down into the door. spray window down with soapy mixture, scrape with the razor, starting at the top, all the way to the bottom, below where the seal will be in normal position. Do this twice.
3- roll window down about 1". cleat the top of the window the same way, but scrap UP this time. again, do it twice. top is more important than bottom.
4- spray the window inside. take backing off film, spray it down. you cant use too much spray. get it WET. put film on window, about 1/2" below the top edge of the glass. squeegie water down. about 3/4 way, roll window up, squeegie the rest. dont roll window down for at least a week.
if your back glass is a compound curve, pay to ave it down single piece or it will look like crap.
i'm sure youtube has videos to learn from.