Conceiving a Boy
Are you hoping to sway nature's 50/50 odds in your favor of conceiving a boy? If you're already the mother of girls, don't be fooled by statements like, "If you have 2 or 3 daughters, the odds are 75% of having another girl" -- because it isn't true. Statistically, population data proves that no matter how many children of the same gender you have, the next baby still has even odds of being a girl or a boy. (See The Odds of having another Boy or Girl.)
Or, if you have heard that some men only make X or Y sperm and so can only father boys or girls, take heart! This is a myth as well, because all men have virtually equal numbers of X and Y sperm. Also, statistical analysis has shown that having only boys or girls doesn't "run in the family", although it can seem that way.
You can try these "low tech" methods in the privacy of your own home, and for free! However, there is no proof that any of these methods actually significantly improves your odds of conceiving a boy. Includes Shettles and more.
High tech methods are clinically proven to give you the best odds for having the desired gender, but they are expensive and inconvenient because you must get pregnant using either artificial insemination or IVF. Includes MicroSort sperm sorting, PGD, the Ericsson methods, and more.