You can also use Goo Gone, that citrus smelling stuff, it works wonders getting the sticky residue off your car or plastics without leaving any marks. As for remove decals and stickers from your paint. I would personally use a hair dryer to heat up the sticker to get the glue behind it a little loosened up then pick away at it. I would try to avoid any sharp or pointy objects to accomplish this. Given the fact they nick the paint when trying to remove them.
I personally have found the hair dryer and dental floss method works quite well and does not leave any marks behind. But this method I have only used on removing the Grand Prix badges and the 3800 badges. I never tried on an actual viynal* sticker though. Though the hair dryer as mentioned above would help in removing those stickers and a little finger picking should do the trick there after. Followed up by the Goo Gone stuff to clean up the sticky aftermath.
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