...the most overlooked thing for a newbie, odor! ...you need to get you a carbon filter if you don't have one bra....if not, everyone in the neighborhood will know.
Man, I read that title and thought " FARM ".
I dont think you will have a problem with 12 plants. Unless you are packed in next to more people.
How far away are your closest neighbors?
If it gets really bad you could use a masking agent like....
Yard inscent's.