Self Directed Study - Value Studies

Over the past few weeks I have been exploring painting in photoshop since I haven't used the software properly for painting, which resulted in my first year projects not looking as good as they could have been. Since I've picked concept art as my specialisation, I have been doing some value studies to get a better understanding of painting and Photoshop, below are the value studies I have done. One is Blood Moon Alkali from League of Legends and the other 2 are value studies of zombies where I referenced the Walking Dead.