These sketches are great. Some good shadows. You look like you know the basics. My advice is practice, practice, practice. Carry a sketchbook and sketch when you are waiting in line or for food, etc. I sketch in a sketchbook but if I don't have one, I sketch on my phone. Sometimes it is like homework and sometimes it is lots of fun. I'm much faster in the sketchbook with ink or ballpoint. I think it helped my painting to think about a line/stroke and then put it down.