get a cool shade lamp that couples to the extractor fan ( preferbly an accoustic one -got a 4'' one second hand on e bay for £70- for cool growing conditions and decent fresh air flow ( v. important ). Install a 8cm or so PC cooling fan ( e bay $1.50 ) at the bottom for air intake. Most importantly fit a 100mm filter to remove any smell.
You' ve then got your basics covered. Fresh air, no smells, very little noise ( can also fit silencers to in line fans to reduce the "woosh" noise of moving air ), and no heat - all of which attract unwanted attention.
With the size of the cupboard you have would consider sticking to indica dominant strains that will not get too high or wide -e.g chronic or ice
You then come the THE MOST imporant thing - tell NO ONE.