ONE. You need to buy eco black lights. Lots and lots of them. A few days before the party, we went and bought several of the round black light bulbs. Big mistake! They are cheap and act just like it. They don't illuminate the room at all. Definitely go for the ECOBULB (swirly bulb). They are $8 each, but are worth every penny. Because they only use 13-watts, you can party with these bulbs for the next 7 years.
TWO. Cover the walls in black plastic table cloths and/or trash bags. Our walls in our apartment are a few different colors, so making them all the same made everything look similar. Plus, you can draw and paint and write all over trash bags! Can't do that on the walls.
THREE. Show your artistic side. Lupita bought neon-colored paints, so we splattered and hand-printed and wrote our names all over the walls. Some of the colors don't glow, so make sure you test the paints with a black light before wasting too much time on painting things that won't glow.
FOUR. Find what glows. Once we got ahold of a hand-held black light, I would basically go to my party supplies and craft box and just scan it. You may find some things that you didn't know would glow. These pink balloons that I hung from the ceiling (with fishing line) and many of my scrapbook pages glowed.
FIVE. Buy a few bottles of tonic water. It is used to make mixed drinks, but we just used it to put in old, empty bottles and set in front of a black light. They were really bright blue and looked pretty cool. We also put a little of the tonic water in ice trays to light up the ice. Apparently, tonic water tastes really bad, so you don't ever want to add too much to damage the overall taste.
SIX. Make sure to have lots of highlighters for your guests to use. Our friend used a highlighter to write a birthday message in the "hole" in her dress :D However, I will let you know that highlighter is a lot more permanent than I remember it being as a kid. I scrubbed and scrubbed, but it would not come off. If you have a job interview the next day, be sure not to use any.
Having a black light party was a lot of fun. I think I had the most fun playing around with tonic water and seeing ice and different things glow. It was a pretty awesome way to bring in year 21.