If you need a dust sheet, make one from canvas or heavyweight cloth, not plastic; it will absorb paint that might otherwise be trailed through the house on shoes. If you must use plastic, cover it with old newspapers.
Before painting a window frame, rub a stub of candle wax onto the glass next to the woodwork. Afterwards, scrape the dried paint off with a putty knife.
If you use tape to mask a painted area, remember to remove it before the paint dries. If you forget, cut along the edge of the tape with a craft knife; otherwise you'll peel off the fresh paint.
Because skin forms on the surface of paint, seal the tin tightly when you have finished using it and store it upside-down. When you re-open it, the skin will be at the bottom of the tin.
Mask adjacent surfaces while painting trim or moulding with an old metal venetian blind slat. A piece of sheet metal or thin cardboard, on a ruler coated with masking tape, also works.
