Always use separate brushes for oil painting and water-based medium and make sure to clean properly at the end of every painting session.

Wipe off any excess paint using a soft tissue. Gently squeeze the bristles from the ferrule edge outwards to remove paint from the brush.

DRinse the brush in turpentine or thinner if you've been using oils or lukewarm water if you've been using a water-based medium. Never use hot water as it can expand the ferrule, causing the hairs to fall out.

Wash gently using a little bit of mild soap. Dab the brush gently onto the piece of soap, and then work up a lather in a small container Rinse and repeat until there's no trace of any color coming out. Over time a brush may become stained, but don't stop rinsing until you're sure there's no paint left.