This one has always been normal practice for me since my mother taught me it to me as a kid: You can usually get three cups of tea out of two tea bags. Just set the two used bags side after steeping, and then use both of those simultaneously for the third cup. I have found that this works well for most green and black teas, but not so well for infusions and white tea. I'm sure some tea enthusiasts will taste a difference but to my uncultured tongue the third cup is not much different. Also I find that things taste better when they're free.