WORKING WITH STRAIGHT LINES (for a T-SHIRT)

A friend of mine wants me and him to work on some t-shirt designs. He already printed one of my drawings on a black shirt, and it doesn't look bad, but I was thinking in a bigger design, maybe a face or face and a foot, or maybe just a foot and the PALANCA brand name together. So I started to play with the mouse, maybe it doesn't have rich lines like the ones I achieve with the pencil, but the results seem kinda interesting. I gotta try both ways, I guess...