Some tips
Thanks again for the nice comments everyone.
I used a set of Sharpie Neon markers which are fairly easy to find. There are five colors to the set, but two colors can be used together to create additional colors like brown and purple. I had to buy an extra set or two because it took that much ink to cover all the cards. I also used two Stabilo Neon fine point markers to color the flesh tones because the Sharpie colors were too intense. They also came in a set, but I only used the 040 and the 054 mixed together to create the shades of flesh tones.
I didn't use any fixative spray; just markers. I had no problem with colors bleeding from the faces to the backs... but I did have occasional bleed through from the black markers used on the backs of the cards. Actually I went over the backs several times to get a deeper black, and went through a good number of wide-tip Sharpies. It took LOTS of scribbling.
For some of the patterns, it helped to lightly sketch a design on the cards with pencil and in a few cases with a compass. Then I'd fill in the colors, paint-by-number style.
The white border on the back was drawn with a paint pen after the black was applied.
If you create a black light deck, you'll obviously need a good black light to get the full effect. I have a 48" black light fluorescent tube positioned about 5' above the cards.
I've been hoping to do a box tutorial if I can just get around to it. There already are some tips on Aeclectic; some of which got me started.
rwcarter, I wish I could make you a deck! Actually, I hope to someday publish a black light deck with original artwork.