As Dru knows, I trim also...I recommend reading Ed Rosenthal's book "Marijuana Growing Tips"...in it there is a chapter on trimming for higher yields with pics and description of how to, why, and what happens when you do trim...I tried it and it worked for me. As the others here who trim have said, just don't go crazy cutting fan leaves off and your plants, or buds, will thank you for it....later on, so will your head! ONLY trim if you just can't get light to that bud any other way, but just make sure all the buds get ALL the light they can for that 12 hours.