People disagree on the absolute best way to clean makeup brushes, but most methods are essentially the same; they just disagree on what’s the exact best soap to use. Here’s an easy guide!
Rinse the brushes in lukewarm water. Take care not to oversaturate the bristles near the ferrule (where the bristles are connected to the handle). If the bristles are wetter here, they can swell and even fall out: a process that is hard to halt once it gets started.
Apply a small amount baby shampoo and lather into a foam. (The technique is similar to lathering with a shaving brush, if you’ve seen it, only a little gentler.) Ordinary hand soap will work too if you don’t have baby shampoo.
Rinse under lukewarm water again, until the water runs clear. Again, take care not to wet the bristles near the ferrule.
Squeeze gently with a tissue and leave sideways in a ventilated area to dry. This may take a couple of hours, but be patient. Trying to speed up the drying process with a hairdryer, say, can distort the bristles and damage the brush.