Instructions
Choose dark clothing. Most necromancers wear a dark cloak or dark robes over dark clothes. Some necromancers dress in skin-tight leather clothing (only if you've a good figure) and a dark cloak over the top of it. Many carry a staff. Some will wear clothes with skulls on them or wear jewelry made from skulls.
Remember that most people consider necromancers "evil" and "scary." You'll want to act accordingly. Look intense, hold people's eyes with your own, give evil, small smiles and avoid helping others. You want everyone to be too scared to go near you when you're in full necromancer mode.
Be a loner. Necromancers aren't sought out; most people don't want to be around them. At your Halloween party, keep to yourself, carefully observing everyone. Stare back at anyone who makes eye contact with you or give small knowing looks.
Offer to bring the dead back to life or offer to speak to the dead. This is your job as a necromancer.