For Tamiya paints, my first step is to fill the cup half full of 70% IPA, swirl a brush in it to get the paint off the sides and then I dump it without spraying. Then I fill the cup again and spray at 40 psi into a garbage bin, working the nozzle back and forth while spraying. When it's sprayed through, I repeat and then put the AB away. Every month or so, or sooner if I get issues, I'll take the whole brush apart and give it a thorough clean with lacquer thinner, taking care not to get it on any plastic or vinyl seals. I'll also lube the parts when I reassemble.