Avoid certain Emo fads, like cutting yourself (very dangerous). Remember that cutting doesn't make you anymore emo, it just makes you stupid and hateful to yourself, and honestly, if your really true to the Lord, you'd know that He doesn't want you to do that.
Remember the stereotypes that are not true and explain to people who think differently: Emos cut themselves (this is not true), Emos cry a lot (not true), Emos have no friends (again, not true).
Emos are often dissed, just as Christians often face persecution. Don't let it get to you!
Don't confuse this with goth. Goth and Emo are two different things.
If you feel God doesn't want you to be Emo, don't be. God has great rewards in store for the faithful! But remember that God rewards not your 'being Emo'. He rewards the motives in your heart that pleases Him, and the deeds that are done because of these motives.
Stay away from 666, triangles, and stars.