Or, "How do I make it look like I've trapped vengeful spirits?" Here are some samples. Different things burn in different colors - here, blue is alcohol and yellow is lighter fluid (like for a barbecue). Buy it by the gallon, you'll use it. Denatured alcohol works, but its blue is just barely visible - it doesn't cast very much light. Lighter fluid is cheap by the gallon, bright, and pretty easy to get. I'll be trying citronella tonight.
Spirits. Put a small amount of alcohol (several drops in this size) in a jar, roll it around to coat the glass. Light it and it will burn in a sputtery fashion - too narrow of a jar and it won't burn at all. Champagne glasses are too narrow, wine glasses are about right. The streamers are me relighting the jar because it kept going out (too narrow to get airflow).
Grill lighter fluid. You'll want a long lighter - I use a brazing torch, an aim-n-flame works too. Like most flammable liquids, only the fumes of this are flammable - but you have to heat up lighter fluid for it to emit enough fumes to burn. And then it'll burn hair off your hand if you're using a bic lighter, and who really wants crispy stubble?
If you're in a place where you won't set anything on fire with accidental spills, and nobody will see flickery flames to call the fire department, this looks pretty cool in buildings. Aurelie is sitting next to a firecup (Corningware dishes are heatproof, as long as you don't drop hot ones in water they're fine), with others lighting the columns. She's backlit with the rainbowgun, which looks downright blue next to the fire. You white balance people will want to shoot in RAW or use tungsten, and any other light source will look blue.
Here's Shutter spinning poi. Even his kerosene wicks look white next to the lighter fluid burning. This much fire made the drain heat up pretty significantly.
So that's some of what you can do. Alcohol-based things have enough fumes to spark right up, but you have to warm up lighter fluid for it to catch. Any questions?