I'm currently reading and studying the book titled Sketching Masterclass, by Ruzaimi Mat Rani and Ezihaslinda Ngah. It's got a lot of helpful stuff in it. I recommend checking it out. I'm also plan to continue reading and studying Human Anatomy Made Amazingly Easy, by Christopher Hart. And I may continue studying Anatomy for Fantasy Artists, by Glenn Fabry, soon. One thing I recommend when practicing or studying drawing is to focus especially on the parts that are most challenging for you. If you're studying a book about drawing, focus especially on the parts that are the biggest challenges, and maybe focus on them first.