I'm a freelancer in a very social, who-you-know field. I am also a HUGE introvert. But just as I have to allocate some of my social spoons towards my workday, I allocate some towards networking. Going to the pub with my coworkers on a project is not my idea of a brilliant evening, no matter how much I like them individually, but I decide in advance that I'm going to go on X day for one to two hours, show up, chat to people and then go home. That, for me, even though it is so casual and non-compulsory, is part of my work. I started because I noticed that people do talk about the people who never ever show up, and I didn't want to be one of them. So now I go enough that people feel like I'm part of the group and keen to spend time with them, but it's planned in advance so I can not spend too long there and relax by myself the next day. I also make an effort from time to time to catch up with coworkers individually. A noisy pub late at night with ten other people is dreadful, but a quiet coffee with one other person is nice. So when I refuse the umpteenth invitation to go out at night, people will just say "Oh, she's not antisocial, pubs just aren't really her thing." Work socialising is never just fun, it's always a bit of work, so you should treat it and prioritise your commitments that way.