after you have thouroughly cleaned it, use a paint scraper (new blade) to remove any crud, then it spray it with a fine mist of water then use a window cleaners squeegee to 'clean' it, dont touch it again, dont use any form of paper towel, this will leave bits.
try not to move around too much either creating dust during the process.
Vansport in Penzance did mine (bit far for you to travel though) £30 all in per window. No hassle, great job; no dust or splits. I can guarantee 100% that if I'd done it myself it wouldn't have been half the job that they did.
Out of interest, where did you get your film from and do you know the make/manufacturer.
Some of the dyed polyester single ply material going about wont last 6 months without fading even in our climate and the adhesive breaks down. Remember when you go to a bonafied pro its not only thier ability in doing the job its the product being used, dont assume all window films are the same.
I did some years ago on a bay i had and did a good job,BUT i do remember thinking damn i wish i cleaned them more , but also spray the window with water with a very fine mist and then apply the film to that, then work from the centre out with a soft lint free cloth to get any bubbles out(Old T shirt),(Dont use a yellow duster).Good luck.T:
ps I like the idea of using templates to cut the film first, cos its very thin and tears easily its hard to cut round the edges to get it precise onto the window,
was thinking of doing my own too but not knowing one film from another...didnt want to shell out,put man hours in only for it to peel 6 months down the line.Going the profesional route now as 2 side windows and the 2 barn doors at the back....£100 quid!!! Not worth thinking about reallyT:
clean the window in and out then spray the outside of the window apply to the window with the protective film facing upwards then cut to size followed by getting all air bubbles out with a heat gun/ hair dryer then spray inside of window remove protective film and spray the tint then apply and use a sqeegie job done T: