Two OIl Paintings and a Gouache which is still Work in Progress

Hey everyone! I feel ive struggled with this particular exercise between wanting to make the image look good and faithful to the creature im drawing and understanding the form and structure. Im quite happy with the monkey and the frog personally but even so, the frog seems less blocky and more like a drawing on the frog with lines indicating form. Any feedback would be very much appreciated! Thank you :)