I know I haven't gone much into my artistic background here in a while, but I have to say: I'm
a pencil girl. It's an animation school thing. I learned to wield many kinds of pencils there. But design school: it's all about pens. Mostly. Or at least it was last year. We had this class in second year that was pretty much draw-for-design-with-only-pen bootcamp. Scariest thing at first, ever, for me! But it ended up being pretty awesome.
At first, we just practiced drawing straight line after straight line, circle after circle, basic perspective: the point being that you gain confidence in your strokes and therefore can use the pen confidently. You can't erase pen. That's the point! You have to put it where it ends up. I still struggle with this (and actually feel like it's more of an Industrial Design rendering thing...), but it's super-useful for Designers of all sort.
We had assignments every week to draw different things (ending with a multiple page flipbook!) and one of them was to freehand alphabets in as many different styles as we could.