Oops - I don't know what I pushed, but I wasn't ready to post!

Blacklight is best when you don't also have regular light. The effect can be really magical because anything black is completely invisible. We once made dancing pink flamingos by putting kids in neon pink tights with foam shoe covers, foam bird wings and bodies which wrapped around the kids' waists, foam flamingo heads on rods, and feather boa necks connecting the heads to the bodies. The kids wore black clothes, gloves, and black Halloween hoods with the black mesh faces (usually for Angel of Death costumes) - and no one could tell how they did it. Underwater and flying scenes are also great because the puppets can float through the water/air - just make sure that the room is pitch dark and nothing behind the puppeteers glows, or the effect is ruined.
Signs really are a great effect in blacklight, too. Our favorite method is to print our images on neon paper with thick black outlines. We cut out the image, glue it on black foam-core board, and touch up the edges with a black sharpie. This is very labor intensive, but makes a durable, rigid sign which glows great.