eviromental factors play in more than you might expect. If you have a closed off room a dehumidifier is critical. CO2 will increase yeild as well in a closed off enviroment. Then of course without decent temps you can ruin everything. Assuming you have your room clean, pest and bacteria free, then lights prob have the most positive effect. Strain is always an issue too. And those are the main mechanical factors that increase yeild. I dont believe in nutes being all that diff from each other, so as long as you have something decent meant for the girls in the right proportion you should be ok. Then if you already have all the above figured out technique comes into play. Short internodes prob have the most to do with phat nasty buds. But that mainly comes from correct enviroment. You can us products like bushmaster to keep plants at optimal heights... the list goes on man, but i think i got the basics here.