Rule #1 - Keep your pencils sharp. I always sharpen 2-3 pencils so I don't have to stop when the creativity's flowing.
Rule #2 - Invest in a white eraser. The pink ones on the end of the pencil can smear.
Rule # 3 - Remember there are 2 ways to draw with a pencil - with the tip and with the side.
Using the tipA very sharp pencil can give you a precise line that is great for drawing the shape of an object. The tip can also be used for:
--Cross-hatching - lines drawn close to each other overlapped in more than one direction.
--Stippling - dots placed close together for darker areas and further apart for lighter.
Using the side of the pencil gives you a blend of graphite. Create a value scale from dark to light. As you blend your pencil marks put less pressure as you get to the lighter side. To make an even darker area add more strokes from the opposite direction.
Now try it on a circle. Decide where the light source is and leave that the lightest area. Use a white eraser to brighten up white areas