Of course the best way that you can perk up Emo hair is to add a few colors to it. Bright pinks and blues look rather good with the bleached blonde background and this is by far the easiest as dark hair will need a little bit of bleach beforehand to keep the color in place. Of course if you are willing to spend the time needed on your hair then you can always use colors on dark hair such as greens and blues but they will generally tend to be much harder to make the color come through and may not last as long.
When it comes to colors for an Emo style, you can go for either a temporary or permanent one, both of which have their advantages and disadvantages. Temporary will obviously not last as long but can be the better option if you cannot have the colors in your hair all of the time.