I overworked this one too much, but I had fun paintig the frog.  It is oil on paper that has been tinted with watercolor and sealed with acrylic matte medium.  It's a technique used by one of my favorite illustrators Paul O. Zelinsky.  I saw a step by step demo of it somewhere online but I can't seem to find it now.  Here is his website where you can see the amazing things he has done with the technique:  http://www.paulozelinsky.com/rumpelstiltskin.html