Write lyrics that reflect on relationships or other personal issues. Emo music is known for lyrics that are introspective and often sad. Try to dig deep and find the lyrics that express the emotions you want to share, whether it's grief, regret, anger or something else.
Write a vocal part. Like the lyrics, the vocal part is usually performed in a very emotional way. Many emo singers sing in a high range to help give the part its emotional, agitated-sounding style. Also, remember to write a catchy chorus that will sound big and showcase the full emotion of your song. The chorus is often the catchiest part of the song and is repeated multiple times.
Write a guitar part. Emo guitar parts are often full of arpeggios or heavily strummed guitar chords. Emo guitar parts are often heavy, driving and played with distortion for electric guitars. Likewise, bass guitar parts can follow this style, though bass players don't usually play chords.
Write a drum part. Emo drum parts are typically heavy. During the verses drummers often stick to hi-hat, bass drum and snare drum. During the choruses, the drummer will often move the hi-hat hand to a crash cymbal, where he will hit strong eighth notes to help give an intense, emotional sound. Also, include fills where necessary, to help drive the song forward.
Include a quiet part before the end. Emo music often has a quieter interlude or bridge before the final chorus. Certain instruments might drop out, and the guitar parts often become more sparse and less driving than earlier. Likewise, the vocal part is usually a little more hushed near the end but might have the most personal, emotional lyrics of the entire song. This is where the vocals are often featured the most. This part of the song also builds tension by pulling back (volume-wise) before building to the powerful end.
Close with a loud, powerful ending. After the tension-filled bridge part, many emo bands close with a very loud, powerful chorus or other part, creating a powerful release for the listeners.