Assuming there will be test prints involved (that is, you won't be working exclusively with the screen), you'll want the lighting to be full-spectrum and daylight-balanced. If it looks good "in broad daylight" it will look right under just about any lighting conditions. I figured that out the hard way when I was painting -- there's nothing quite like putting a couple of hundred hours into a work then finding out that the colours are all horrible everywhere but in your studio. Back then, it took a balance of fluorescents and tungsten to simulate the right light, but these days you can get some really excellent fluorescents. (My personal preference is Ott Lites -- Lowes carries them in a standard Edison-base spiral 25W version -- but there are other brands and other retailers.)

You'll want it to be fairly bright, but not uncomfortably so -- you certainly don't want to overpower the monitor. You might want to have at least two lighting circuits so you can keep the level lower for heads-down computer work and turn up the volume a bit for examining prints. For critical examination of prints, the light needs to be brighter than you'd think a sane person would allow -- it's really the only way to judge values around Dmax. I can't give you a lux level, but I found that 100W (four 25W CFL bulbs) in a ten-foot-square room is just about right for viewing prints, while I can get by with one bulb during straight computer work.

The walls should be as neutral as you can make them. White is good, but it can be a bit much to take all day, every day. A neutral grey (not grey card grey, just a titanium white "tinted" only with a neutral black to an "off-white" value) is probably never going to be high style in the decorating world, but it won't influence your print colours or make your eyes readjust their white balance when looking at and away from the monitor. A white ceiling can help to maintain the light level without the eyestrain that white walls would cause.

Apart from that, make your workstation comfortable. Invest in a good chair -- you're going to be living in it for a considerable chunk of the day. If you don't have one already, get a tablet (like the Wacom Bamboo Pen or, better yet, a larger Intuos). Once you've used something that works on absolute screen coordinates (top left of the tablet is top left of the screen, bottom right is bottom right), you can never go back -- you'll really begin to wonder why anybody thought that pushing something like a bar of soap around the desktop with no reference points could possibly have been a good idea. If your monitor isn't hooded, you might want to build a hood for it -- it's really easy to get used to the slightest glare, but that glare affects your judgement. Oh, and did I mention that the workstation should be comfortable?