I currently have one, and he's resilient (he was the only one to survive the bout of Marine Velvet that decimated my tank). I feed him an alternating schedule of frozen brine shrimp and TetraMarine Flakes.
Personally, mine likes to take shelter under any rock. I would make sure to provide many hiding spaces for the firefish. As Kremis noted earlier, you must be sure to have a lid on the tank. In my experience, they will not jump unless harassed by other fish.
I keep my tank around 82 degrees Fahrenheit. Ammonia, Nitrites should be absolutely 0ppm, and I would keep Nitrates under 5ppm. He was able to tolerate some neglect and I would recommend him as a beginner fish if you are just starting up. He was the first fish that I added into my 75 gallon.
I am not sure how susceptible to diseases like Ich or Velvet they are. I have heard cases of a couple of firefish dying of unknown causes, but I have heard cases like that in a bunch of fish.
Good luck!
(liveaquaria.com also is a good source for water parameters and gives a good overview of the fish.)