I own and run a sign shop. For decals I use a clothing steamer to heat up and soften the vinyl decal and then it peels right off. I use a special glue remover, but the next best thing is goo gone. For the badges I use fishing string behind the badge to cut the double stick foam tape and then heat the residue up with the steamer or a heat gun and it then will roll off the paint by rubbing it with your fingers.

 

I just took some decals off...I used wife's hairdryer, some spray-on Goof-Off in some spots, and the decals peeled right off. The key is heating the decals a little. Try to do inside in warm garage if possible. Otherwise, just let Jeep sit in the sun for awhile like I did and then go over a couple minutes with regular hair dryer then peel off with fingernail. The adhesive stays on the decal, not the Jeep. Any residue just hit with the Goof-Off (I guess it is the same as the "Goo Gone," others are talking about just different brand.) I used the newer spray on Goof Off which says on the bottle safe for removing bug & tar from automotive finishes. This version seems safer and more diluted than the original Goof-Off in the concentrated can so look for the spray bottle version. Afterwards, just washed area and hit with some quick spray wax & never knew decals were there.