It looks nice... One suggestion. If they are twins, you should make them look a bit more like each other... Otherwise it'll just look like two girls. One thing I noticed was that they have different noses. Try to make their facial features match. That's a bit part of having two characters look related ^.^ I hope that helps.
i agree with catgirl... you should draw them a little more alike so they couldn't be mistaken as 2 best girl friends... although there are some twins that don't look alike... >.<
eniweiz.. other than the proportion and the pencil lines.. it looks nice to me.. <3