What hairstyles would suit me?

My sister has layers, no bangs, a round, heart like shape face and I'd want to know what I can do to her hair to make it better. She can't do plaits/ braids or whatever you call it because her hair sticks out.She just wants to impress her mates for the school prom- she's in year 7- or first year of high school. So please help she deserves it and she also has dark dark brown hair. She likes updos, but she needs a proper makeover since shes a goody two shoes a school never got into trouble. Anyway, what can I do to help my little geek of a sister. Please also note that this is my first question and i'm not very used to it. Lastly, she can do little plaits or braids or whatever but only the 3 section common one since the others stick out! HELP ASAP!!!!!!!!!!!!! :D