Deluxe Draughtsmanship Exercise CheetSheet(TM donut steel all rights reserved lol no not really)
Draughtsmanship is the skill of making lines go where you want them to go. For that, body, eyes and mind must work together.
Some movements feel awkward and your pen won’t go in the direction you want it to. That’s a body problem. Exercises like the radial and (clockwise/counterclockwise) circular training will help you build muscle memory.
But round arcs and straight lines are of no use if they don’t land on target. For that, practice three-point targeted circle exercises, circle push and ellipse exercises.
Jumping the gap between 2D and 3D is going to be the hardest part. You have to train your eyes. The problem is that the page is flat and your eyes will see that. Eliminate all shadows with a well lit surface. Defocus your eyes, close one eye (or cover it) to defeat your depth perception so you can see INTO and draw INTO the page rather than ON the page. You have to push your lines AWAY from you or TOWARDS you.
Lastly, some of these exercises are meant to be DISRUPTIVE. They break routine and pattern and force you to keep your mind engaged instead of falling into stupid autopilot mode. Good art requires a certain amount of mental fortitude. These exercises are meant to provide you with a level of cognitive difficulty to strain your mind.
Look at your own abilities (or lack of them), pick one to strengthen, and then choose the exercise that targets that weakness. Practice until it becomes second nature and then move on to the next weakness.