Step 1: Wipe off the excess
As soon as you finish painting, wipe the excess paint off the brushes.
Step 2: Wrap it up
Wrap your paintbrush in cling film. Make sure it's fully sealed so the air can't get in and harden the paint. Next time you want to decorate, simply unwrap the brushes and get going. No hard bristles, no endless rinsing, no sweat!