Nothing special but this is what i do...
I take thinner, put it in extra airbrush jars, jam my brush down to the bottom and spin it around in the corner removing all the paint then I let the brush sit upside down so as the bristles will spread apart and dry nicely. If the brushes get a little hard no biggie, dip them back in clear thinner, and flick them on the edge of a piece of card board, it will soften them right back up... I have 2 seperate bottles one for earth toned paints and one for more like auto paints (ie;purple, reds, etc etc)....
Then, because I work on armour alot, after you have cleaned your brushes enough using earth tone paints, I let the bottle sit over night, then siphon off a little over half of the portion of the thinner, and use that as a wash on my tanks.. to simulate dirt and mud build up in the seams.... Hope this helps