When you want to make a line you don't have to plan your line with actual lines on the page. Just hover your pencil ever so slightly above the paper and do the line a couple times without actually doing it
As if you were going to hit a golf ball with a club, you practice it a couple times till you feel you've got a good shot
Also you're still symbol draw, I recommend you google planes of the head and draw a bunch of stuff like that, but the key thing is to be thinking of the 3d aspect of it. To check if you've got it down try to draw one at an angle you don't have a reference for from imagination
