The single most useful principle I’ve found for deciding on social engagements is the Derek Sivers decision making principle of “If it isn’t a HELL YEAH, it is a no.”
The principle isn’t universal as there are many decisions that need to be made with less than 100% certainty. But, I’ve found it to be spot on with social engagements – especially if you are introverted.
As introverts, we face a lot more downside from a crappy social engagement. So, it pays to be selective. :-) This principle helps us do just that.
But, perhaps the meta principle here is to find and use a principle that works for you to make decisions in areas like social engagements. Decision making is work. And, principles help make the process much easier while delivering consistently better outcomes.