There are many different ways, and many different products that are used to clean makup brushes. I have watched countless youtube videos on how different guru's clean their brushes. I have kind of merged them all into one, to create the method I use.
I (try) to deep clean my brushes once a week, but really need to invest in a product that enables me to spot clean them, (i.e MAC brush cleanser) I use so many different colour eye shadows, that by the end of the week, the amount of makeup that comes off my brush is, well, disgusting!
Also not washing your brushes can cause spots, so I like to keep them clean, and it does only take about 10 minutes, depending on how many brushes you own.
If you have any brushes that are used with cream products (cream eyeshadow brush, foundation brush, concealer brush etc you should use olive oil before the shampoo, to make sure you get everyting out. I do usually use olive oil to clean my normal eye shadow brush too, as I use it a lot).
I'll do an example with my cream eyeshadow brush.
Run the brush under water.
Then squeeze some shampoo onto the sponge, and when the brush is wet, again swirl it in the shampoo to ensure that the brush is properly clean.
My lovely clean brushes!
How do you clean your brushes?