Whenever you draw something small with the pencil tool, it tends to be angled instead of round. So when I draw small circles they come out looking like diamonds.
Usually I intend small details to be rounded rather than jagged, so I spend a long time recreating details.
Is there a quick way to round out edges? The "smooth" button tends to exaggerate angles rather than smooth them.
When you select the pencil tool, look at the bottom of the toolbar window. The last item at the bottom is the option for that tool. The default is a stair-step looking line. Click and hold on that line and you should see two other options available, try the smooth option, it should do what you want.