1. Celebrities
Celebrities don't always do the right thing when it comes to friendship, and that's the point. They make mistakes and end up on the news a lot, and that helps because it gives you insight into what's really important when it comes to friendship. Sometimes seeing someone else (even a celebrity who you don't know personally) can help shed some light on the best way to treat a friend.
Not every celebrity example is a negative one, of course. Oprah Winfrey and Gayle King seem to make their friendship thrive. Ben Affleck and Matt Damon have been friends since they were kids and are still close, and there are several other celebrity best friends who provide positive examples on friendship.
2. The Playground
Think back to the times when you were running around on the playground. Didn't it seem as if making friends was easier when we were kids? That's because you were less guarded and more trusting. As adults, we've dealt with years of people being dishonest and hurting us, and as a result we aren't as willing to forgive and forget as we once were.
It's not always a bad thing to go slowly in relationships, but if you are putting up walls when you meet new people you are doing yourself a disservice when it comes to friendship. Talk about the issues you have with your friends, and learn to develop more trust. Think back to when you were a kid and use that as a guide for how to be more open in your friendships.
3. Work
You might be surprised at some of the lessons you'll learn from observing people at work. While the office is a professional setting, it's still a good place to see how people interact, how they maintain loyalty, how they choose to disagree (and resolve those disagreements), and how they cheer each other up. The office (or wherever you work) is an interesting place because people are forced to be together who aren't necessarily friends, so it's a good learning experience to see how they choose to treat others. Even if you don't have a friend in the office, you'll benefit from watching your coworkers.

