Pencils com in a wide array of options. You can pick up a box of designer pencils like the ones you see to the left. Or you can just individually pick out 2 or 3 that will work for you. I'll try to explain what factors should influence your decision.

The chart to the right shows what the different "Grades" of pencil are. You've seen the infamous yellow #2 or 2B pencil all your life at school. Now looking at this chart you can see what that means. H = Hard lead. Hard lead makes a lighter line and is used mostly for drafting. 9H is as hard as it gets.

On the opposite side of the spectrum are the B grade pencils. B has a soft lead so it makes a darker line. 9B is like mascara.
I choose the middle ground. an HB or F pencil has a nice versatile grade.
Back to Materials I use Mechanical Pencils so I don't have to sweat sharpening them. Staedtler Mars makes a set that has a "Lead Weight" ring on it so I can rotate it to the weight of the lead I loaded it with. That way I can have different pencils with different lead weights loaded..the ring tells me which is which!