Some beginning artists are really good with traditional media when they start out, but switching to a digital tablet is hard for them. I´ve been there. The tablet doesn´t respond like e.g. a pencil, where you can feel when marks are left on the paper. On a digital tablet it just is too smooth without much feedback.
Here is a quick tipp:
Tape a piece of paper to your tablet! It is a whole other feeling when drawing digitally. It won´t make you a better artist, but it sure helps.
You can even put a whole stack or a sketchbook on top, which gives you an even softer surface.