This article is from the Choosing Your Baby's Sex FAQ, by Roger A. Hunt email@example.com with numerous contributions by others.
Mainly the vinegar douche, and timing conception.
This was 23 years ago, so I cannot remember the
details. I don't think I knew my cycles were longer,
and therefore, I ovulated longer. For me, I think
the Vinegar made me too acidic, and therefore killed
the sperm. We tried for 9 months. The one time I
did not douche, we got pregnant, and guess what, a
wonderful son, who is now an adult !! Sigh. Never
did have that daughter...