If you are looking for a totally cool emo punk rock style ala Fall Out Boy, check out this tutorial. In it, you will learn how to tease up short hair into fun messy spikes. This method works fantastic for men and women with super cropped locks.
Wash and condition your hair
(optional) Crimp your hair
Dry your hair
Take up clumps of hair, starting near the top of your head and working your way toward your bangs, and comb them downwards until they stick up. Spray them with hairspray.
Touch it up, spraying any parts that were not long enough to tease