Just peeled off the old crappy window tint with little difficulty.
However, how in the heck do you get the glue off?!
Acetone? Laq thinner? Heat gun?

 

ammonia...seems to eat it off.. I personally like windex and some of the Cheaper ones you can find at the Dollar store....

-Tape/cover...and anything else you can do to protect the door panel (remove if its easy enough)...
-Squirt the window down really well
-use a single edge (scraper type) razor

**Tip**The solvent will act as a lubricant for the razor to prevent you from scratching the glass... If a spot starts drying up, re-spray it... (you should Not hear any scraping noises from the razor)

The old glue should clump together as you scrape....have a towel/trash pile-can ready

On Edit: I normally use 3-5 New blades per "avg." sized side (drvr-pssngr) window.

 

Just use straight ammonia in a spray bottle and work it with a razor blade. Just don't let the ammonia get on the interior. It may blotch the plastic.