So, you want to be a goth teen? Great! This is Lydia, and she's the Princess of the Undead.
Step 1: Make the commitment to go on this goth journey solo, because loneliness is a key ingredient.
Step 2: Pick an unusual accessory!
Step 3: Perfect your sullen "Really?" face.
Step 4: Pull a creepy non-sequitur.
And then relate it back to your own goth self.
Step 5: Goths prefer darkness, so pick outfits that look best in subdued light.
Step 6: In fact, practice a shocked face for when you're forced to see actual sunlight.
Step 7: Become a voracious reader of all things disturbing.
Step 8: Always look like you're filled with anguish and despair.
Step 9: Never EVER smile. Unless you're in the presence of the undead, and then it's fine.
Step 10: When it comes to hair and makeup remember this: BLACK!
Step 11: Actually, just remember BLACK for all aspects regarding appearance.
Step 12: Get a new hobby that involves taking photos while dressed like a witch.
Step 13: See dead people.
Step 14: Pretty much just hate everything.
Step 15: Try to invoke unholy spirits to be your BFFs.
Step 16: When faced with a "normal" social situation, make everyone around you uncomfortable.
Using a line like this should suffice.
Final step: Take a dance break, because goths secretly love dancing.
Especially to Harry Belafonte.