It can be hard at times, but I would say finding an interest is a good way to find RP. Especially plug-in related interests. For example if you play and hang out at volleyball courts, then you can ask others simply to "play?" and then after strike up a convo. You can do the same with other plug-ins. Another idea is joining classes, and chatting with the people next to you, or the teacher. Applying for roles is another route, like professor etc.
If you do want to learn how to approach people, an easy way is to go up to someone and giving a compliment or mentioning something that they're doing.