In a perfect world, you would be washing your brushes once a week.
I only wash mine every few weeks at best, which is not ideal for keeping your skin healthy.
To wash my makeup brushes, I use this cleanser by BareMinerals, but any gentle shampoo or facial cleanser will work.
When washing your brushes, use warm water and always angle the brushes down so that the stream of water goes in the same direction as the bristles. If you run the water directly into the center of the brush, the bristles will get tangled and the brush may not reshape well.
I squeeze a small amount of cleanser into my palm and after thoroughly soaking the brush, I delicately swirl and rub the brush into my palm until it lathers and I can see the makeup pigment seeping out. Then, I run it under the faucet until the water washing through is clear and all the excess makeup is removed.
Before setting them out to dry, gently reshape the bristles as close to the original shape as possible so they can maintain their integrity.
The result: beautiful, fluffy, clean makeup brushes.