What is the best way to train batteries for a long life?

I recently replaced the battery in a friend's iPhone 3GS. He was complaining of a short life, so we get a new battery. Installation was a breeze. For years I have heard dozens of contradictory opinions on the methods and reasons for training new batteries. My question has three parts...

1: Is battery training a real thing that someone with a new battery should do?

2: If battery training is real, what's the best way to do it?

3: Assuming this is the absolute truth, where or how did you get your information?

I appreciate the feedback, and I think the battery will too :)

EDIT: I am wondering about a process for extending the lifespan of the battery right off the bat. For example, with some batteries I have heard that charging them to 100% and discharging them fully several times when they're new will make the battery store charge longer. I am looking for a proven process to achieve that function of storing greater charges for longer times.