"If you want optimal protection for fading and scuff resistance then you must use optically clear vinyl overlaminate. However, if you want the utmost visibility through the perforated window film, then you can't vinyl overlaminate. In this case an aerosol spray overlaminate could be used prior to install and make sure that liquid does not plug up the perforations. Please note that if you do NOT use vinyl overlaminate it is very difficult to see through the perforated window vinyl when driving in the rain.
"Ammonia based products, such as Windex, prevent the adhesive in window mounting adhesives from sticking to the glass. Instead use soap water, Rapid Prep, or alcohol to prep the surface."
"When installing window perf or other vinyl, many glass surfaces have wax or other invisible coatings on them (like RainX) that interfere with adhesion. Place several drops of water on the glass, if the water forms into beads there is a coating that must be removed. If the water does not form into beads there is no coating and you can proceed to clean with isopropyl alcohol."