To properly store paint, clean the rim of the can to ensure a proper seal. Pour 1/8" (3mm) of solvent on top of oil-based paint, or 1/8" (3mm) of water on top of latex paint to seal the surface, then secure the lid. Alternatively, stretch plastic wrap over the can opening, replace the lid securely, and store paint upside down. This will create an airtight seal to keep the paint fresh until you're ready to use it again. Always store paint away from heat sources at temperatures between 3 degrees and 35 degrees Celsius, and out of the reach of children.