While it might be tempting to simply wipe down your guitar or bass with any soft cloth lying around the house, it's probably best to invest in some dedicated polish cloths (though, to be honest, old t-shirts are pretty good options as well).

You want to make sure that the cloth you use to polish your guitar is non-abrasive and will not possibly scratch the guitar's finish. While most guitar-specific polishing cloths will suffice, many players swear by micro-fiber cloths, which is extremely soft and helps avoid "swirls" in the finish. Other players prefer cloths that are made of double napped cotton flannel, which will safeguard the finish from scratchs, unlike other more abrasive cloths.

Regardless of which type you choose, it's best to clean or replace the cloths often. Fortunately, they're easy to clean and cheap to replace, if needed. Just remember to wipe down not only the body of the guitar, but also the strings and fretboard.