Well providing you actually want to be one, here's the advice I would give:
Get the hair right. It's like what emo girls are known for I guess.
Your buzzwords are fringe, hairdye, volume.
Stripes and polka dots are pretty big, stuff with skulls on it, tight jeans, skater gear, black mixed in with brightly coloured... There's no real rules as such, but somewhere between goth, punk and Japanese cartoon characters is where it's at.
Make up is required.
Emo makeup tip #1: Use eyeliner
Emo makeup tip #2: I mean a lot of eyeliner
Stick to thick foundation, the paler you can go the better pretty much.
Brightly coloured eyeshadow is not a bad idea.
Yes, please.