I use a mechanical pencil for most of mine, and kinda have two lines: Faint soft ones that get erased and harder sharper final lines. I dont smudge much, never really been a problem. And yeah, my first ones were pretty bad... the ones I do now aren't much better... but yeah, figuring out the trick and how to show movement has become a lot easier. Practice makes perfect, but if you're bored in class, its a fun distraction, and you'll improve before you know it.