I first came across the My Very Favorite Art Books by Jennifer Lipsey through another homeschooler, who shared its uses for learning how to draw simple trees and flowers. I loved the illustrations she showed us and thought it would be a fun addition to our nature study.
I found a copy used for a really good price, and then we were on our way!
It has step-by-step tutorials for beginning painting in different mediums (watercolor, acrylic, etc) and the instructions are simple enough that a young person can follow them easily.
I really like the fact that it has so much nature in the drawing side! This has been a good find for us – Emma enjoys pulling the book out and following the instructions, and just being inspired to draw by looking at the pictures.
This particular title is out of print, but you can buy I Love to Draw and I Love to Paint along with other titles in the series on amazon.com (affiliate link) separately for about $8 each new . Or you can find them used like I did on paperbackswap.com or abebooks.com – wherever you like to find your used books online.