Micing is usually the job of the Sound Engineer/Operator. There are two 'usual' positions. Taped high on the cheek, almost at the ear, or taped to the forehead. The later is best when wigs are involved, as the wig easily hides the lavalier mic. The cheek is the easiest position, and is often covered with some tape and makeup applied over the top (especially when you have flesh toned lavs).
Lavs can also be attatched to costumes fairly easily. Combine that with boundary mics, shotguns etc, and micing should be almost invisible to the eye.