When I picked up my '12, I'd already had the dealer remove the 4times4 sticker before I even saw the truck. Well, when I saw it, there was this tacky, godawful, ghost flame graphic extending from the front wheelwells, across the front doors, and ending at the back edge of the rear doors. HELL NO!!!!, were the first words out of my mouth. Get that OFF MY TRUCK!!!! They used some sort of eraser wheel, they called it. The sticker was so large that I wasn't going to attempt it, let alone it being a new truck and me chancing screwing the paint up. They told me that a lot of people commented on how good the thing looked. I almost asked if they may have been from Bangladesh or 5 years old, and watched Ice Road Truckers when they were in India.
Anyway, the wheel did a good job, but I wouldn't trust myself with it.

Like Beechkid said, a heatgun/hairdryer works well, and I've followed up with some of that 3M adhesive remover, then wax. That was on small stickers, and would likely take forever with a large graphic.