Some of the most important ways to boost male fertility have nothing to do with pills or supplements. Sexual technique can be critical to fatherhood. The most likely fathers are not necessarily the "best" lovers. At least during the four days around the female partner's ovulation, generally at the midpoint of her menstrual cycle, conception is more likely if the couple does not engage in foreplay.
To be a little less than polite but to put in a memorable way, "Wham, bam, thank you ma'am" is more likely to result in conception than tender lovemaking--although lack of foreplay is only relevant when the female partner is most ready to conceive. The reason sexual intercourse without foreplay is more likely to result in conception is that foreplay causes the anterior wall (the front) of the uterus to rise. The ejaculated sperm have to pass through more cervical mucus and along a longer route through the uterus to reach the newly released egg. The absence or presence of foreplay at other times in a woman's menstrual cycle is, of course, irrelevant to conception. Also, men are more likely to become fathers when sexual intercourse is conducted with the man on top, in the missionary position. When the man is on top, the penis extends further into the cervix and is forced into a "boomerang" position.
Ejaculation sends semen along the posterior wall of the uterus, on a more direct path to fertilize the egg. Another important consideration in natural male fertility is the question of boxers versus briefs. Boxers allow the testicles to hang loose, especially when the wearer is standing. Briefs hold the testicles firm against the body, where they are kept about 1 degree Fahrenheit warmer than if they are allowed to hang loose. That single degree in increased temperature difference makes a crucial difference in male fertility. At higher temperatures, sperm may be released before they are fully developed. They may have less "swimming ability" and they may be more likely to be killed by unusually acidity in the cervical mucus. These three simple methods are not a guarantee of male fertility, but they are an excellent place to start working on other ways to increase fertility naturally, even before consideration of PCOS, endometriosis, or other hormonal issues in the female partner.