Night dives are wonderful. Buddy up with an experienced night diver for your first time or start your Advanced Certification with a night dive accompanied by an Instructor or DM. If you really love it you can go on to earn the Night Diver Specialty with 2 more night dives.
At night you'll see an entirerly different environment. Coral polyps open up to feed, lobster are out walking around on the reef, BIG fish (snapper, grouper, hogfish, tarpon) are out feeding, Parrot fish are sleeping in slime cocoons, and morays are out free swimming. Squid are also more active at night.
I highly recommend a cylum or some other lighted marker on every diver as well as on the dive flag. PADI recommends two lights per diver. Personally, I think if your buddy team has 2 good lights between them, if one fails they have the other one to use to surface immediatly. But 2 per diver can't hurt and I'm sure PADI has their resons.
When night diving from an anchored boat, the boat should have a strobe suspended for diver reference - depth of the strobe depends on the depth of the dive. A safety bar suspended at 15 feet is also a good thing to have setup for anchored boats. Also, you're have to swim back to the boat, so bone up your navigational skills.
Night drift dives are different. The boat follows the lighted dive flag. You surface - the boat is there waiting for you. Ah, drift diving - the lazy man's dive.
Dive the location first in the daytime and then dive the same spot at night. This way, you will already be familiar with the dive site during the night dive.
Oh, and use night diving etiquette. Don't shine your light in your buddies eyes and shine your light on your hand during comunication so your buddy can see. Don't shine your light at boat. Shine it under your chin or on top of your head.
I do a lot of night diving at Lauderdale by the Sea. It's killer!
Night dives ROCK!!!!!!