Always hang a painting or picture securely, in a spot that is absolutely dry, never above a fire or radiator, nor in too bright a spot (directly expose to sunlight).
Air circulation is crucial so make sure that they lean away from the wall. The good trick how to do it is to glue cork pads to the lower corners of the frame for extra insulation.
Only use metal picture wire and one or two steel or brass picture hooks depending on the size and weight of the painting.Heavy, glazed pictures may also need to be supported at the base on brackets fixed to the wall.
Screw eyehooks onto the frame, never into the stretcher or back board. With a heavy picture, put a pair of hooks on each side, fastening the wire and running free through the upper pair. Then if one hook gives way the painting will still be supported.
Oil paintings must be set in a frame deep enough to accommodate the painting on its stretcher. Sometimes the frame is lined with soft material (e.g velvet ribbon) to protect the edges of the painting. If the rebate is too deep, it can be padded out with cork or balsa-wood strips. If it is too shallow, the frame can be built up with strips of wood.
Mirror plates or brass plates screwed into the frame and overlapping the stretcher, hold both picture and stretcher firmly in place.
Oil paintings are coated with varnish and do not usually need to be glazed. However, if you feel more comfortable glazing the painting to protect it further, then do so. But it is important that it is executed by professionals.
Works of art on paper must be mounted on acid free board. Check whether an existing mount is acidic by looking at the bevelled edges of the ‘window’; if there is a brown stain around the line of the window, the board is likely to be made from poor quality wood pulp and should be replaced.