i've got some experience with growing in bachelor pads. first thing is to scope out the closet space. you should have about 3 sq ft in a small closet to work with, which is good for 2-4 plants (keep in mind maintaining the 4 in good health will take more effort than just the two.) really though, any space can do. i vegged the plants in my first apartment entirely in the same bathroom where i took showers and had people going into for shits LOL.. step inside the closet and close the door. make note of all the places where light permeates at the edges of the door, and measure how much space there is between the door and the frame. you MUST keep light out because any light penetration during the dark cycle can make your fems into hermaphrodites.
your best bet to keep light out while still leaving the door functional is black foam insulating strips from the hardware store. they should come in rolls with glue on one side so you can stick it and forget your troubles. be sure to double check that you've sealed out ALL light tho. this brings us to what may be an issue... ventilation.
odds are, you're going to need power tools to cut the space required for ventilation. don't worry about permanent damage, you can always seal it up afterwards with paper maché and spackle :D just make sure there's a clause in your rent agreement that keeps the landlord out (except for "in case of emergency," as it's usually stated.) for a big space, bigger ventilation is necessary. you can't simply run a few computer fans, because they will either need to run too fast and make a bunch of noise or they won't produce adequate breeze.
what i did for ventilation was carefully shield the bottom of the door instead of using the foam insulation there, so that air could easily pass through but light would not. if that sounds complicated now, don't worry about it. the picture will become a lot clearer to you when you're looking at the grow space, and if it doesnt then you still have a few days before the cotelydons fall, another few weeks before it starts to really stink, and hopefully you've figured out a solution by the time you need to switch the lighting for flowering.
as for fans, look for an inline fan that runs silent (typically around 100 cfm.) you need to then find a thin section near the top of one of the walls in your closet into which you can cut a hole to mount the fan and vent the air, and be sure to attach to the fan as much carbon filtering as you need to kill the smell entirely. it's a good idea to have a wooden framework, some duct tape and ducting to best keep all the air flowing quickly and efficiently through the carbon filter.
ok, on now to lighting. HID is out of the fuckin question for a stealth grow. best solution, imho, is to get an extension cord that's long enough so that you can sneak it under carpets, etc, to a plug far away (and preferably hidden from view) and have it connected to a powerbar in your growspace where you can plug in a few cheap desklamps or simple light sockets with cut up coke cans for hoods. then you want a couple 60-100W equivalent compact fluorescent lights (CFLs.) you'll want to start off with the DAYLIGHT bulbs for vegging, then move into warm spectrum (the normal bulbs) for flowering. i prefer 4-6 60W equivalent bulbs per plant, and the results have always been quite excellent.
many diehard HID proponents will tell you that CFLs can't put out as many lumens as the HIDs, and for that reason are inadequate. truth is though, CFLs are far more versatile and can be positioned to maximize the efficiency of the lumens they do put out, so be creative as far as lighting goes. get sockets with bendable stems so you can position lights on the side of the plants and get light to the lower leaves, or if you're willing to get more complex you can look up SCROG growing and give that a shot.
versatility aside, the real benefits of CFL use are that they won't produce much heat and that they will be virtually unnoticeable on an electric bill. think of it this way... my computer's power supply is 600W, and the monitor consumes 30-60W. a CRT TV and microwave will eat up even more juice, so in the grand scheme running a few extra fluoros won't really amount to shit.
this post is getting pretty long so i'm gonna start wrapping it up here: as mentioned, don't tell ANYONE about it. i couldn't avoid having some people in my confidence, but even your best friend could fuck you over by accidentally letting something slip one drunken night so it's best policy to not say peep to anyone. take a big backpack or duffel bag with you when you go soil shopping, because you don't want to raise any flags should a neighbour happen to spot you carrying a huge bag of potting soil into your apartment. mix the soil over newspaper laid out so you can crumple it up and throw it out without a mess afterwards, just be clean in general and spend the extra dough for good organic liquid nutes so you can make feeding the plants easy. don't bother with mylar and other reflective crap except for the hoods you strap onto your lamps, the white walls will more than be adequate at reflecting enough light. if you have any other questions you think i may be able to answer feel free to PM me, but remember that creativity is the most important thing in a stealth grow and how i do mine may differ from how you choose to design yours. that's pretty much a license to do whatever you want, as long as you cover all the plant's requirements by doing so.
ps. i forgot to mention that the prerequisite CFM of the fan will depend entirely on the space you have available. think of your space in terms of VOLUME, not AREA, because your fan will need to be powerful enough to create a vacuum so air won't leak out the in holes and stink up your place! all exiting air must pass through the carbon filter!
