Hey @pngo!
I have a feeling there are a few things you're not getting beyond ergonomy for drawing - drawing on a tablet is hard but there are definitely tricks you can do to improve your line-quality before moving on to art.
A few key things to get comfortable making art in the digital world:
1 - Rotate your canvas! If you're comfortable making lines on paper in a specific direction (horizontal for instance), don't hesitate to rotate your digital canvas to make drawing easier. In Photoshop, it's holding down the R key and rotating the page around. The escape key will reset the orientation. This can help you get comfortable for line exercises.
2 - Speed! Drawing a line slowly is guaranteed to make it look wobbly. You'll have to build confidence and quickly glide the pen across the page for a chance at it looking even somewhat straight. To build up this sort of confidence with speed, you'll need to set up step 3....
3 - CTRL+Z! The greatest advantage of digital painting is the "undo" button. At all times when I'm making precise lines, my fingers are resting on CTRL+Z to undo the last line I just made. I paint, undo, paint, undo, paint, undo, until I'm satisfied with the result. There is no reason you should move on with a sloppy line you're not happy with - undo it, try again, and only keep the very best.
4 - Draw with a motion coming all the way from the shoulder rather than using your wrist or elbow. This takes a while to develop but if you're making lines by holding the pen the same way you would write a sentence (i.e. using the wrist and fingers), your lines stand no chance.
I hope these tips allow you to retry the exercise with a better understanding of the expected result. Good luck buddy!
