How do I manage all the brushes full of paint when they're not in use?

If you're using the suggested wet palette, you can actually "park" your brushes on it and they won't dry out right away. It's not necessary to use one brush per color, but I do often have several "parked." As long as the brush part of the paintbrush is resting on the wet palette, it should not dry out. I often just dip my brush end in the water bucket so it is very wet, and it won’t dry out while I am painting with another brush. Sometimes, if I am stopping for a break or overnight, I might put the brushes in a plastic baggie and close it to keep in the moisture. If you are going to stop for a day or two, properly wash them out with clean water and a little soap.