if you really wanna cut off some leaves to increase light penetration, start with the really bad looking ones, then the larger ones blocking budsites. Eventually the bad leaves will fall off on their own, but if U watch the "stoned free guide to growing" DVD it says they do it as soon as the leaves turn bad and dont wait for them to fall off. I also follow this method but I only do it within the first 2 weeks of flowering and during the last 2 weeks of flowering so i dont stress the plant too much.
try not to remove too many bcuz the plant will need them to soak in the rays, but if the leaf is turning brown or yellow then the plant wont miss it.
remember anything green has chloryphyl in it, including the stems and buds. chloryphyl is responsible for producing sugars for the plant, as soon as the leaf turns yellow or brown the plant wont need it for photosynthesis, but it will still be sucking nutrients from it... it should be safe to remove if needed.