Once you've completed a painting, ensuring its longevity and quality preservation is essential. Apply a protective varnish over the surface to shield it from dust, UV radiation, and minor scuffs. It's important to keep your painting away from direct sunlight and extreme fluctuations in humidity and temperature, as these factors can lead to deterioration over time. Storing your artwork in a cool, dry place, ideally with archival materials, safeguards it for future generations to appreciate.