Here's a small collection of my artwork.

I'll alternate between pen and pencil, but I like pen because of the intensity of black ink. Unfortunately, pen is a little harder to shade with since lint or whatever kinda bunches up at the ball point causing small random blotches. Pencil is pretty versatile but the darker the graphite the more it kinda crumbles and looks super "grainy". Probably wouldn't be a big of a deal on bigger pieces, but anyway the planet was just drawn with your typical pencil. The rest was done with your ballpoint pen.