The ideal spot for a work of art is out of direct sunlight on an inside wall with no slamming door. These details are from The National Trust Manual of Housekeeping, the operating manual for the stately homes that are England's living museums.
An exterior wall mount can be finessed with bumpers that hold the work proud of the surface so that humidity does not pool behind the frame and condense, causing the mold disorder known as foxing. It's worth reading the book to collect other fine points. I use push pins behind the frame of a work I deem worth the risk.
Current atmospheric changes have accelerated the rate at which sunlight fades pigments and damages fabric, so it's worth the trouble to keep the shades drawn if the room is not in use. Very conservative custodians hang curtains in front of a work.
Use a light hand when dusting a frame, particularly one that is gilded. The manual advises dusting only when you are calm and well-rested, since most damage to inventory happens during maintenance. These procedures come out of a culture that is willing to require a housekeeper to repay damage, ie, a year's wages for damaging a work worth that much. Dust gilding with a soft artist's brush, like squirrel hair. Set the piece on a horizontal surface covered with a clean towel, and dust against the direction the dust settled. Use a dedicated brush and cover the metal ferrule with adhesive or gaffer's tape to protect from nicks. I'd work close to an operating air filter or vacuum opening. Knock dust out of the brush by tapping it against your wrist or the edge of a table.
Take off your rings and touch the surface of the piece not at all. Think of it as an open eye, and leave maintenance to a restorer.
Wear flat shoes and transport a valuable piece in a basket padded with a clean towel, ideally by setting it on a wheeled utility cart. If you transport valuables in a motor vehicle, bring a second person along in case of a breakdown.
-30-More after the jump.