Color studies

Here are some examples of my color studies. I try to make these as often as I can since I constantly find that I learn new things from doing them.
Noah Bradley inspired me to start doing this exercise, and here's one of his great videos on the subject: https://youtu.be/kQfF-P70V2Q
I used the software Mischief for most of these drawing. A couple are made with Photoshop.
The drawings are kept small on the screen. Maybe 10cm in width (about 4 inches). And I use broad strokes relative to the size of the drawing. The idea being to not focus as much on the details as on the relationship of colors and especially on your own ability to estimate which colors to use. So, I don't use the color picker at all, except for the last stage were I compare my result with my reference to see how far off or close I got.