What I do: use tepid water and wet the hairs. Use a gentle baby-type shampoo - nothing with builders or proteins or anything gunky in it. Rub shampoo through the hairs and wipe gently back and forth on a washcloth. This is pretty similar to how I clean my paintbrushes, actually!

Then run the hairs back under flowing tepid water. Use a gentle stream of water. Make sure all the shampoo is rinsed out.

Gentle is the main term used here - gentle rubbing action, gentle shampoo, water that is not at all hot....since this is not hair that will be growing back, you need to treat your brush as a fragile tool to get many years of worthy use out of it.

Then shape your brush head the way you want it to dry, and lay it flat on a towel or over the end of your sink to drip dry. No hairdryers needed - remember, we are being gentle. :)

Washing your makeup brushes this way is much better for the handle and hairs than the old school method of soaking your brushes in a sink overnight. Plus, it saves a ton of money - the brush cleaning products sold in the stores are often really just a very mild, very gentle shampoo that you can find on your own, and for far cheaper price points.

Really be careful to not let the handles get or stay wet. A warped handle will drop airs. High-quality brushes, properly cared for, can last many years.

It's also helpful to keep brushes assigned to one use - liquid foundation on one, facial powder on another, powder blush, bronzer brush, lipstick...all on their own brushes. This keeps them all reasonably clean for longer periods of time. Then instead of having to wash your brushes too frequently (which will wear them out faster), you can just sort of run them dry over a clean cloth to get off most of the color. Microfiber cloths are great for this.

Only do a good water/shampoo washing when the hairs get a bit gunky, ie, when the brush doesn't feel as silky across your skin as it used to.

Of course, this is really all about the GOOD brushes. I recommend the cosmetics brushes sold at Sephora, Origins, Bare Minerals, Aveda, Two Faced, Body Shop, Paula's Choice and Trish McEvoy. Yes, there are other good brands out there, but when you get a cheap brush, you can tell the difference - hairs fall out, the brush texture isn't really all that plush, and your colors don't spread evenly.

A good brush sits firmly in the handle socket and doesn't shed. It has a nice heft in your hand and feels delicious swept across the face. Color is spread evenly and you have a sense of control over where the makeup is being applied. A good brush should never need to be tossed - saving money overall - and is a joy to use.