11/16/12: Design Help!

Hi everyone!  I need some design help. The Acorns sweater I knitted a couple years ago needs a style update. I'm not really liking the black buttons I used before and would like to swap them out with a lighter color--not sure what though. So here are the questions:

what type of button shape should I use?

what color of button should I use?

Give me some ideas!