To Get A Boy (According to Shettles):
Time intercourse as close to ovulation as possible: The idea is that since the Y-chromosome sperm are faster than the X-chromosome sperm, there will be more Y-chromosome sperm who reach the egg, making it more likely that a Y-chromosome carrying sperm will fertilize the egg.
Abstain from intercourse for four to five days prior to ovulation. Have intercourse only just at the time of ovulation and just before.
Have intercourse that allows for deep penetration. Shettles recommends rear-entry (aka, ?doggy-style?). The idea is that the sperm will be deposited closer to the cervix where cervical fluid is most friendly to the Y-chromosome sperm and where the ?boy sperm? are more likely to survive since there is less distance to travel.
Men avoid tight clothes: heat kills off both types of sperm, but will kill off the less protected, smaller Y-chromosome sperm faster, according to Shettles.
Women have an orgasm: According to Shettles, female orgasm increases the alkaline secretions in the vagina that are favorable to the Y-chromosome carrying sperm. Shettles recommends having an orgasm before or at the same time as the male partner.