There are many reasons why a couple may wish to conceive a boy. Perhaps they already have several daughters, or there are already many girls in the family. Whatever the reasons for wanting to have a male baby, following the Shettles method developed by Dr. Landrum Shettles may increase your chances.
Understand the key differences between Y-chromosome sperm (male sperm) and X-chromosome sperm (female sperm). Male sperm are actually smaller, lighter, faster and more fragile than their female counter parts. Male sperm live for only a day or two, while female sperm can live for several days. By exploiting their differences, you can create conditions that favor the male sperm reaching the egg first.
Avoid having sex for four days before ovulation. Since female sperm are extremely hardy, they can survive in your body for a long time while waiting for the egg to be released. They are strong, but slow swimmers, and while the male sperm are dying, the female sperm will be swimming to meet the egg.
Avoid alcohol and cigarettes if you are the father. Since male sperm are very fragile, men who drink and smoke heavily will have fewer male sperm and will therefore be less likely to father a male child.
Have sex on the day of ovulation to increase the chances of the male sperm reaching the egg first. Use an ovulation kit to determine your day of ovulation.
Consider in vitro fertilization techniques. In a lab, fertility doctors can isolate male sperm from female sperm, and fertilize a male embryo. This is not a natural (or cheap) way of conceiving a boy, but it is the most fail-proof.