The MOST important and accessible exercise is gesture drawing. It's great to do with a ballpoint pen. I would suggest starting with the shortest time frame available. Quickposes and Line of Action are awesome websites with more or less comfortable software. Doing gesture drawing will really forcefeed you a lot about how the general human figure moves and looks! Sketching in ballpoint pen is awesome! It is harder to fix mistakes, but it forces you to be more intentional. Additional resources: Practice Drawing This (it has a great website with 3D models that you can manipulate and rotate, and many of these shapes are what you will later use to construct bodies); Bridgman's Constructive Anatomy (it is a book, and you can find a free PDF online; even just copying the illustrations there really helps your form); other 3D model sources (a mobile app called Magic Poser and SketchFab; you can get versatile references of your preferred angles, as well as get a good look at the parts of the face or the body that are confusing to you). As an observer, the drawing is actually fine! It's stylized, appealing and the characters have a lot of emotion.╰(*°▽°*)╯
