ignova said:Honestly, I wouldn't worry too much about those brown tips unless they seem to be getting worse. Most likely it was caused by some minor issue with the watering or other stress in the plant's past life. Misting won't improve anything. ZZ plants grow very slowly, so you might have to wait a long time for new growth. So long as the new growth looks good, you should be on the right track.
GraceHazel said:Brown tips are typical for lots of plants, probably minor physical damage or chlorine from your tap. This plant does not benefit from misting, but you should wash off the leaves or just wipe them off to prevent dust buildup. If you water more than you pay your rent, it's too much.