I installed the side stripes before...I think??? they had some reference dim's in the package or something, was along time ago though.
I would use bug/tar remover to clean the work area, then like Isopropyl Alcohol aftrewards to prep the it..this will remove and wax and grime...Little nerds stuck on the paint will show through the decal, and trap air around them...Not good...Been there had that...
I used masking tape to kinda set my points top/bottom and you can even run the lenght of the angle down the door then lay your decal edge against the tape ..you can measure and mark accordingly with tape..
Leave an 1/2" extra to wrap around the door edges to..you kinda roll it around the edges for a clean look.
I used a spray bottle with a tsp of dish detergent in it....spray the area with plenty of that...you can slide/reposition the mother quite awhile with that..if you have to peel it up and reposition it, you have time with that water/soap solution..just wet the area down again...KEEP THE ENTIRE AREA PLENTY WET...dry spots will kill you..
I used a soft damp cloth to get the major water off and then work from the center out...air bubbles suck to get out as you goota push em to an edge...
PLENTY OF SOLUTION...WORK GENTLY FROM THE CENTER OUT.you dont want to stretch em..Its almost a one shot deal cause after you kinda seat it and push the air/water out and she's there..Pull it up after you did that step and it'll stretch the decal and it wont quite seat right again...
Don't worry about them sticking cause of the Windex or solution you use..once you push them down solid..they stick like a mofo and ain't coming off....Take your time and you'll be fine...dry run the fit a fine times...tag em with small pcs of tape to hold em and stand back and look...Good luck..