Makeup brushes are great tools to use for applying foundation, powder, bronzer, blush and highlighter.
But, makeup brushes need to be cleaned, at least once a month to avoid the spread of pathogens. I recommend washing your brush in Dawn Liquid Detergent or good quality shampoo. Apply a pearl size drop of cleanser on the brush and wash, swirl around in the palm of your hand with a bit of warm water. Then rinse until all the brush runs clean. Repeat until the water is clear. Let the brush sit out to dry over night. And you're good to go.
Most cosmetic companies sell brush cleaner and some companies sell drying stands and other gadgets to make brush cleaning easier. It doesn't matter how you do it, just do it!
I recommend: www.realtechniques.com These brushes are very well priced, and you can buy them at Ulta or Bartells. How great is that!