I deep clean mine about once a month (but I could probably do it more often to avoid build up). I use the Sephora daily brush cleaner to spot clean it, and I use Johnson and Johnson Baby Shampoo to deep clean. Get it wet under luke warm water, put some of the shampoo in your hand and swirl it around. Rinse it out once you feel the brush is completely clean and lay it flat to dry on the edge of the sink. I hope that helps!
I clean my brushes daily with a spray brush cleaner to wipe away obvious traces of makeup, oils, color, etc. I hand wash them with gentle cleanser (I recommend either Philosophy Purity or baby shampoo) once a week. This keeps my brushes clean and bacteria free, causing less breakouts, and helps my brushes perform optimally.