Have you ever tried to tell a story about yourself only to have someone interrupt with a story about themself?
On more than one occasion I have heard people talking and this same instance happens. Person one is telling a story about something that happened to them when person two says "that reminds me of something that happened to me" and continues with their story. Watching the face of person one when this happens is priceless. It's the "really???" face.
This can also happen around a dinner table. Someday you will realize you didn't actually have a conversation, but a competition of who could tell the best story. Obviously it is ok to talk about yourselves, but make sure the other person is done talking. There is nothing more frustrating than being interrupted.
The best advice for a healthy friendship is to listen and respond. If you respect others by letting them tell their story, you will get time to tell your own.