Have you recently felt depressed? Alone? Abandoned by your family and friends? Misunderstood by the world? If you have, and like to express your puzzled feelings and emotions in poetry and music, chances are you're what today's society considers "emo".

Steps

Understand what emo is. "Emo" has many meanings. Some would say its only a genre of music, categorized by hardcore music with sad, emotional lyrics. Others consider it only a brief way to call someone "emotional". Still, there are those who believe "emo" is a lifesytle and choose to live their lives the "emo" way. Like any style, fashion or culture, the exact definition is up for debate and often varies according to personal expression. The term emo is loosely associated with emotional rock; most emos like underground or indie music.
Appreciate emo music. Emo is a rock music genre, usually consisting of emotional lyrics and optional "screamo." Over the years, this music genre was usually seen as underground until recent times, making emo music more popular than ever. This music sometimes consists of lyrics seen by many as "whiny," and "sensitive." Listen to a lot of emo bands, and maybe even consider picking up an instrument, such as a bass or guitar. Also try the violin, if you invest enough time into it emo songs on the violin are incredibly emo-sounding. The drums can also be a very good instrument. You may even want to write your own songs by writing poetry and turning it into songs.
Test yourself. Try listening to emo music. If you end up liking this type of music, and come out sobbing after you’re done with the album, you’re probably a "true" emo. Getting inner emo is all a matter of finding out of you have it or not.
Dress emo. After you have discovered your inner emo, try shopping for a new wardrobe. Emo fashion has roots in both punk and goth. Wear tight jeans, tight shirts with emo band logos on them, studded belts, and an old, black and worn down pair of sneakers. Thick, black-rimmed glasses are not uncommon for emo guys. Also, stripes and checkers are big in the emo culture.
Get an emo hairstyle. Dye it black or brown with perhaps some blond or unnatural color streaks, especially in the bangs. If you are a girl, you may possibly want to cut your hair to a very short bob-like hairstyle but keep your bangs long, swept drastically to one side and covering your eye. Or, for those who like long hair, get many choppy layers and highlights. For a guy, you may want to spike up the back side, and pat down on the front side. You could also get your bangs/fringe dyed a lighter color than the rest of your hair.
Get the attitude. A lot of times, emo is associated with being bitter, depressed, insecure and resentful. But at its core, you can be emo because you're sensitive, introspective, thoughtful, and quiet. Don't ever be loud or in anyone's face; focus on your own emotional life.

Tips

When applying eyeliner, do not be afraid to apply to the inside of the lids, not below, it adds a more dramatic affect.
When shopping for emo clothing, be sure to check stores like Hot Topic, Vans, and Spencers (for accessories), you will be able to find most of what your looking for there.
Remember, that you CAN wear other colors than black. Though black is a very popular color among emos, you don't want to wear too much or people might mistake you for "gothic" (NOT a good thing).
Do not try too hard to be emo, others will see you as a poser.
Do not go around telling people you are emo, let them figure it out for themselves, or they will call you a poser.
If someone asks you if you are emo, simple shrug your shoulders or deny it. If they asked you, chances are, their opinions are already made and then your approval isn't going to change it much.

Warnings

Real emo music is not popular and will be hard to find in most music stores.
Do not tell people that you're emo or that you are trying to be emo, let them figure it out for themselves, or you will be called a poser.
You may be subjected to negative criticisms by your non-emo friends and possibly the majority of society, just ignore them.
I will not tell you that cutting yourself is bad, in some ways it does help, and I'm not going to criticize you, bit I will warn you, people do not think highly of "cutters" and will not treat you kindly if they find out. It could even lead to more serious consequences such as counseling. If you do cut, do not make it known and be aware of the consequences.