April 21, 20170 found this helpful
Stretch a piece of plastic wrap over the open paint can before closing the lid. This will create an additional seal to keep the paint fresh.
Keep the leftover paint in a cool dry area to keep it from spoiling and becoming unusable.
Label the lid of the paint can with the color, brand, room it was used for, and the date it was opened.
Keep any and all contaminants out of the paint cans. Dirt, dust, oil, or just about any foreign particle or substance will contaminate your paint and make it unusable.
Keep it away from direct sunlight or near any inflammable object.
Turn the can upside down to allow the paint to create its own seal.