Take the time to clean your brushes! If you continuously use the same brushes on your face, not only with the make-up build up in the brush, but so will the bacteria from your face.
An unclean brush will lead to unnecessary blemishes and prevent the makeup from going on as smoothly as possible. You can purchase a brush cleaner from most beauty supply stores and make-up counters, or you can use a little bit of shampoo and water to clean them effectively.