i have heard that if you germinate them in birth control water soaked paper towel it increases the percentages by 10%
if this was so, don't you think we would all be doing it? just remember, most all of us grew up hearing about Santa Claus too. (not bashing on you, OB... just the whole birth control pill thing... been hearing it for decades now
)
being male or female is a genetic trait that has been predetermined in the seed DNA. there is nothing you can do to increase the odds of a female other than using more seeds.
Feminized seeds allegedly do increase the odds of having a female, but they also seem to increase the odds of having a hermie... so, you have to see if maybe it would just be better/cheaper to buy more regular seeds rather than spend the extra dough on feminized. (i say allegedly because i have never bought/tried them so i wont say it is so.)
what you CAN decrease the odds of happening though is your plants going hermie on you. a good stable grow op with proper temperature ranges and good ventilation/air flow will reduce or even eliminate your hermies in your crops.