An easy home solution that I use is this...

- Peel off the sticker, leaving only the gooey stickey crap.
- Take some fingernail polish remover and cotton balls. Make sure that the cotton balls are 100% pure cotton, otherwise some other crap can scratch the paint.
- Soak a cotton ball in fingernail polish and rub in circles over the gooey stickey crap. (Repeat with new cotton balls periodically)
- After a few mins, it will start to come apart and you can wipe it off with a wet rag.