If you're looking for a beginning point/opening into this practice, this one is decent. It provides some background and reasons why it is useful, including what it does to the sides of the brain, then spends a great deal giving prompts, exercises, and examples.
I could never give a book 5 stars that doesn't use an Oxford comma, but aside from that glaring issue, these authors just don't cite their research well. Especially when discussing the brain functions, they don't directly cite their sources, which horrified me!