There are two broad types of social problems people can have with parties. The first is that a lot of people don't like them that much. They find parties boring, stressful, and draining. They want to know to avoid them, or minimize the damage if they have to go to one.
The second issue, which this article will cover, is when someone wants to go to a party and socialize at it, but they're not sure how to do that. Some problems people run into are:
Feeling shy and awkward about approaching people to start conversations.
Not knowing what to say when they're chatting to someone. Introducing themselves, as well as the ensuing conversation, can feel stilted and forced.
Not knowing how to break into group conversations. This particularly comes up if it seems like everyone at the parties knows everyone else. It can feel hard to intrude on a bunch of friends.
Not knowing how to speak up and stand out once they're in a group conversation. This especially applies if the discussion is loud and energetic and all over the place.
Not being great at dealing with the rowdy, zany aspect of parties.
Just not knowing what to do with themselves. Is it bad to stand around too much? Are they obligated to make the rounds and try to talk to every last person there?
Feeling like a party is a big social exam and that how well they do at mingling is some sort of reflection of their overall value as a person.