Pre-shrinking is more important for things such as back windows, or any curvy glass. Every car is different as far as tint goes. Custom cuts aren't that hard, tell her to harden the f*** up. To shrink film you just spray the window and film a bit, squeege the water down, respray the film then lightly heat it with a thermo gat(heat gun, hair dryer, etc) while using the squeegee to straighten the "fingers" out. You only want to heat it enough to cause a "zig-zag" effect in the straight "fingers". I wouldn't recommend shrinking film for the fronts unless you have plenty of film.