Actually there is a scientificly proven method...Here it comes...the big evil "e"...exercise. X sperm are tougher and can survive the heat and weird stressess of exercise better. By killing the male sperm off there a higher chance of a fermale sperm fertizlizing your egg. Also by havinf sex durign yuor peroid the sperm have to wait around and that kills off more male sperm than female. Higher chance of your next egg being female fertilized. THere's no 100% method, but these should at least scew the odds a bit.