One of the most important thing you need to think about is ventilation, you need to move alot of air and keep your temps stable. OK, figure what your budget is going to be. dont forget to include nutes, ph meter, pots, trays, seedling-cloning set-up, ELECTRICAL IMPROVEMENTS unless you want your house to burn(seek professional help), ect.... How much space do you have to work with ? are you going for quality or quantity ? How much gardening experience do you have ? SIT DOWN and draw a layout or a plan.
I built my room in June and just harvested my 1st batch of some premium purp, some local experienced growers were impressed i am happy to brag about!
READ! READ! READ! Check the "sticky's" at the top of most forum sections for excellant tips, it will save you alot of time waiting for answers.
I started with a 1500 budget which quickly went up to 2700 with 2 x 1000w lights with fans, cloners,ect..... Are you growin with chemicals or Organically ? Soil or Hydro ? Alot of prep work will pay off in the long run.
Good Luck.