I watched the guy do my tints last time I went

clean the glass with a squeegee or whatever it is u call it
cut the shape from outside
he used some liquid to stick it to a window he had at the shop and left it there for a little while
he they sprayed the similar stuff all over my window (and door panel )
put in the film and cut the excess
used the credit card-style palette to push out creases
job done ... that's what I reckon