Don't use other mediums with your good watercolor brushes
. Oil and acrylic paint aren't as gentle on brushes as watercolor pigments and will ruin watercolor brushes immediately. Likewise, keep your fingers off the hairs of your brushes. Your hands are full of oil, and your face is even worse. I actually see uninformed customers fondle new brushes and touch them to their face like a makeup brush. It takes all the finesse, patience, and diplomacy I have to not scream. Good brushes are expensive and should be respected, not fondled.