Make the most out of your cosmetic brushes by cleaning them regularly. Wet your cosmetic brush. Take a small amount of a natural shampoo in the palm of your hand and make circular motions with the brush . Rinse the brush under running water, continuing to make circular motions in the palm of your hand until the water runs clear with no bubbles. Don't allow water to extend past the bristles. Gently squeeze the bristles to remove excess water. You can also use conditioner to condition the brushes. Leave the brush tilted on a towel to dry.