Don't use furniture polish on a guitar! These products contain silicone, which will then get transfered to the case, and anything else that it touches. If you take a silicone-tainted guitar to a luthier, you could contaminate their shop, ruining any paint or finishing work they do. That stuff is almost impossible to get rid of, and it stays around for a long, long, time.

Use guitar polish on the body, the back of the neck, and maple fretboards. Lemon oil works well on rosewood fret boards.