I've have done THOUSANDS and THOUSANDS of windows up to 52" wide... I can knock out a window pane in 8 minutes (prep, install and trim) I did full storefront wraps at a very large retailer over the last 5 years...almost 1 or 2 a week all over the state of Texas.
The way I do it..
PREP THE WINDOW
-Windex the dirt and cobwebs and what not off.
-Alcohol the whole window. Pay careful attention to the corners where a "waxy" type film can be present. Make sure the glass does not have a slick feel. Sometimes I have to resort to brake cleaner to get the waxy stuff off
PREP THE PANEL
-Keep the panel rolled up.
-Unfurl about 1' and trim off the backing
-Keeping the sticky side out, take the roll and climb up the ladder
ALIGN
-Visually line the panel up with the mullions. I like to work with 0 bleed at the top to make this go faster, but if you have 1/2 or 1" bleed then I start on the mullion.
-I press a finger spot on the left and right of the panel just to hold it for 5-10 second
APPLY
-Take a large squeegee (I use the Bill Collector) and start applying up from where the backing paper is cut. Doing this will get it almost 100% flat without tracking or wrinkling.
- Once you apply all the way up, ensure the panel is straight by looking at how it hit when you went up. If everything is Kosher, proceed down.
-Start pulling the backing down and apply from the middle out using LIGHT pressure. Heavy pressure will cause the material to stretch and track.
-Sometimes it will want to wrinkle. Once it starts doing this, I usually apply DOWN instead of side to side. If you apply down from the beginning, it will start to wrinkle bad once you get close to the bottom. Usually I can go side to side up to about half way down the panel before I start to feel it wrinkle..then I apply down.
Once you get confident and good, you can actually rip the entire backing off and "tension" the panel on the mullions so it's suspended just off the glass, then you can apply down. Plus it looks cool when you rip the whole backing off at once...just don't do it on a windy day.
TRIM or PACK
-Trim to the caulk line with an xacto. I use a straight edge so that way even if the caulk is all wonky, you still have a straight line
-If your trim is removable.. remove it, pack the vinyl into the edges and put the trim back. I use a flat head screw driver to get it started and pull it off. I get all 4 out, apply and then wearing a pair of gloves, pack the trim back in. Gloves help because that stuff will turn your fingers black.
Some things I learned..
-Applying dark colors in direct sun substantially adds to the difficultly. Gotta go slow with that.
-Using real light pressure at first apply is key. Heavy pressure tends to stretch the material and cause wrinkles.
-The most time consuming part (at least for me) was aligning the panels. I like having 0" bleed at the top so I can just visually line it up and go. Only time this is not good is when the windows are not the same size, not straight or angled. 9 times out of 10 this is not an issue but occasionally you'll find a store with some really jacked up windows sizes.
-Even with the uppers and lowers.. I still work from top down even if the window is a rectangle. I do this too keep all the panels in line and not track.
-Apply only in the daytime.
