There are people out there who don't know how to, or even to, clean their makeup brushes. This is just a quick video showing you how I clean my makeup brushes.
I do this every couple weeks, getting all the makeup and bacteria off my brushes.
Lay your brushes flat - keeping brushes upright in a jar is fine when they are dry, but when they are still wet water can get into the ferrule (the metal part of the brush where the bristles meet the handle). This will ruin your brushes, breaking down the glue, having the brush separate from the handle.
Sanitize - using alcohol or a cleanser with sanitizing agents in it will prevent bacteria from growing in your brushes, and going onto your face.
Cleanse Often - Even if it's just a spot clean with alcohol or brush cleanser, cleaning will help prolong the life of your brushes and keep bacteria from growing on your tools and transferring to your face.
I hope this helps!