My husband and I use Billings. We learnt about it from an instructor and we also have the book mentioned above. We have been very successful with it, and so have lots of people in our families.

You check your mucous mostly by sensation and then supplement your knowledge with observation. If you feel wet or damp, but you don't see anything on your knickers or when you wipe you still count it as a fertile day.

And people say you can't ovulate twice in a cycle, but they're wrong. I have ovulated twice in a cycle too.