The default Pencil is nearly impossible to draw with. It’s even worse to try and draw fast with and fast is the name of the game when drawing comics.
DOUBLE CLICK the PENCIL TOOL icon in your tool palette.
A fly away menu will open and give you some settings to play with that look like this picture.
The .05 FIDELITY and 0% SMOOTHNESS settings are what I have found work best for me. Play around with them and draw with the PENCIL until you find what works for you.
It is Imperative to click the KEEP SELECTED option OFF. If you keep this box checked it’s very hard to draw with the Pencil tool to mimic a real pencil.
If you draw with the Pencil Tool and the Keep Selected button on then the computer erases each line you draw as you draw a new one.
I rarely use the PEN tool at all to draw in Illustrator. I find the Pencil tool does what I need and it’s a lot faster than the Pen tool.