It depends on the style that you want. Basically, Emo hairstyle are unconstructed and unblended look showing lots of texture. If you do a search for
Emo Hairstyles, you'll find a ton of pictures to choose your look from. Once you have the cut, blow dry with some gel or a mousse, and then a pomade will give you that broken up grunge look that many of the Emo style have.