Do not handle miniatures after eating, scratching your head, picking your nose or when you have generally dirty fingers. "Your fingers will be dirty and oily if you have not just washed them". The oils, dirt & grease that your fingers pickup can get transferred to your miniature. Water based Acrylic paint does not stick well to a surface that has grease or oil on it. Also dirt from your fingers gets rubbed off onto any really bright color you may have already painted, such as Yellow or White.

Before painting a miniature, I always dust it using a brush (something soft, I use a makeup brush) because it's really aggravating when a piece of lint is painted into your miniature, It can be seen.