Okay so here's a simple style I've been trying to perfect. It focuses on the eyes/mouth/hair. I can't use vectors to make these though. (My program of choice doesn't allow for Vectors.)
Feel free to use them. I'd really appreciate advice on these heads, or just how to make a clean look in a head.
I really like this one, the facial expression saying 'meh' I just love it. As for the other one, I couldn't tell what it was. It seems like you just went all random cause you could not think of any other ideas for a head. But I cant really talk much, I make art, but I haven't tried textures.
I also advise adding a watermark to your flats, wouldn't want them getting stolen.