Sometimes people have lots of potential friends in their lives and they just need to do more to try and hang out with them and start a relationship. But the opposite is just as often a problem, when they don't have many friendship prospects around. In that case they have to meet some.
Below is a long list of my ideas of ways to meet new people. Once you've met some people, you can take the other steps required to possibly turn them into friends. It's all about being proactive.