You can simply not be Emo if you do not have the right hairstyle and although the more unique is generally considered to be better, there are some guidelines that you can follow if you are a beginner to the world of Emo.
First of all, most Emo kids adopt the look of the reverse mullet. This is generally longer at the front than it is at the back and is rather difficult to do at home by yourself so perhaps it would be better to have this look professionally cut at the hairdressers? Although this reverse mullet is very popular, it is not unusual for an Emo kid to have one length hair with a lot of choppy layers chucked in for good measure and this applies to both guys and girls.
One of the most well known trademarks for the Emo look is a longer set of bangs that simply must cover one eye. This is almost considered to be a symbol of the Emo kid not wanting to see the real world and also not wanting others to get to know the real them so has more meaning than just a simple hairstyle.
Experimenting is normally a big thing for Emo kids and with regards to this, there are no limits. Spikes are great for those that have shorter hair but are trying to grow it out and again this applies to both boys and girls of an Emo following.