Here are some principles I apply to friends in deciding whether a friend is worth the time and effort of sharing my life with them:
1. Three Strikes and You're Out
If I reach out three times to hang out or initiate conversation, then you will become an acquaintance. Friendship is a two-way street where there should be a mutual interest in each other's lives. It's not fun to feel like you are always initiating or trying to brainstorm for things to do while the other person is lounging around, waiting to be entertained.
2. It's Not Always About You
This should be fairly straight-forward, but hanging out with somebody shouldn't mean a 1 hour+ session of listening to mundane details about their lives and problems without a cursory inquisition for the other party. Of course, it's different when someone is going through a major life event and they need support, but if we are casual friends, let's just say I'm not thrilled if you find the most titillating part of our hangout to be the main discussion: you.
3. Reciprocate, Reciprocate, Reciprocate
Things happen. Priorities change. People are busy. But not texting someone back and then doing so after a month has passed, and then not following up to my text right after about that responding text is an indicator that you don't really care for me. Exception: overseas/out-of-state friends. But I still have buddies who live in faraway places yet still are on top of their social media game like Kim Kardashian, so, shame on you.
I do realize that this post comes off as a tad cutthroat in sorting out friendships or worse, trivial in trying to box people into specific categories. However, I find it to be less emotionally taxing than wondering why I feel so drained after spending time with someone (newsflash: you shouldn't feel so after being with a friend, no matter how introverted one is) when I apply these rules. Plus, it's less frustrating than trying to figure out where you "stand" with somebody and feeling rejected and exhausted after realizing that you're always the one making plans.
Always be proactive rather than reactive.