What unnatural color streaks? HELP!?

I have dark brown hair, stick straight, and a little past my shoulders. I have hazel eyes, and am pale and short. I want unnatural color streaks in my hair, but I don't what color. I was thinking blue or red, but then i had thoughts about green and purple. HELP?!?! I also have bangs, so i don't know if I should get a streak or two in my bangs! Will it look stupid or emo? I don't want to make myself look even uglier that i am. How long will it last? Am I making a stupid mistake? Will it damage my hair?