Hanging
The use of backboards is recommended as a preventive conservation measure to protect against the accumulation of dust and dirt, as well
as against knocks and accidental damage.

Never expose the art work to extreme heat, extreme cold, or to extreme humidity. Avoid hanging work in bathrooms and storing in attics or damp basements. Works on paper are susceptible to mold and mildew if exposed to humid conditions for more than 24 hours.  If conditions are
not rectified, the mold that forms will remain active, and can cause color changes and foxing – dark spots resulting from enzymatic activity of microorganisms.  Humid conditions will also provide undulations in paper that can rub against the glazing.  Should mold be detected, it is best to unframe the work, expose it to dry, clean air, and reframe with acid-free materials.  Avoid storage in dark, musty areas.

Rubber bumpers on the back of the frame allow air circulation, help keep the painting level once hung, and prevent marring of your walls.

Housekeeping
As with all objects in your home a painting will collect dust and dirt. Dust can be removed using a very soft brush or cloth. Avoid feather dusters and sheep skin dusters, however soft, as they catch. You must be careful to check that there is no paint flaking before dusting. Do not attempt any dusting if the surface appears unstable. If your painting has glass this will need cleaning from time to time. Always spray glass cleaner onto the cloth, not the glass. Spray well away from your painting. If something happens to your work of art do not attempt any repair or cleaning yourself. This is a skilled process and should only be carried out by a fully qualified conservator.

Good art is an investment.  With time, your investment will grow and your purchased art will increase in value. If you resale or gift a work of art, please contact the artist,  informing them of the work's new whereabouts in order that the work's provenance records can be updated.

Handling and storage of Pastel Paintings
When protected by glass pastel is the most permanent of all media, for it never cracks, darkens or yellows.  Pastel works have been proven to last as long as, or longer than works in any other medium.  They will preserve their color and distinctive matte surface with the same freshness as when first applied.

Pastel works are protected most effectively by framing as this will avoid accidental smudging and abrasions, and the settling of dust. Check that your framer is fully conversant with the requirements for pastel framing. 
Please be sure that fixative is not sprayed on the pastels this spray will destroy the matte surface and change the color of the work.  I have applied fixative to my paintings during their creation, but to avid dulling of colors, the final lay of pastel must not be sprayed. For glazing, use only anti-static materials to avoid having the powder lifted off the surface of the composition. If the framed painting is handled roughly, small particles of pastel may detach themselves; they are easily removed by carefully taking off the frame and using a kneaded rubber eraser on the mount and a lint free cloth on the glass.

Handling and Storage of Watercolor Paintings
Watercolor paintings are meant to be framed behind glass.

Do not place anything on the surface of the painting.

Avoid touching the surface of the painting.
Oils from your skin can damage paper and leave marks that cannot be removed and paints can easily be disturbed by the oil or dampness on your skin.

Do not hang in areas with bright sunlight or high humidity.

Handling and Storage of Oil paintings
Oil painting is a sturdy, long-lasting, and durable art form, and with proper care and handling will last for generations.

Never lean the front or back surface of a stretched canvas on a pointed or sharp object, no matter how small. This will leave a dent that will disfigure the work. Handle an oil painting by the frame without touching the painted surface. Prolonged exposure to direct sunlight will fade the colors in your oil painting. Do not let dust build up on the surface of the work it will dry out the paint and possibly result in cracking and peeling. Do not use any cleaning products on its surface. If the surface of your painting looks dry and dull, you may want to have it cleaned and revarnished by a conservator. Also take it to a conservator if it needs repair. For temporary storage or transporting an oil painting, place cardboard or plywood on both front and back (slightly larger than the outside dimensions of the framed oil painting) and then wrap in ‘bubble wrap’
and tape or tie securely. Do not keep it wrapped up long, moisture may buildup and cause damage.

Permanent storage should be in a custom-sized plywood container with the painting braced to allow air flow on all sides without shifting.