Ooooh I never get questions like this! Honestly, I think the number one best advice I can give is to be active on twt. Follow writers you like and people who post things you like, interact with posts beyond just liking, reach out to authors of the fics you enjoy and dm them and tell them how much you enjoyed their work(s). It can be a little scary, especially if you're shy like I am, but putting yourself out there is really the key. As you do this, you'll naturally pick up mutuals, and those easily form into friendships, and then you'll meet more mutuals and friends through them. You'll find writer friends specific through this process

It also helps if you use your fics to get involved in the community. Obviously, events are an option, but also making promo tweets/threads for your fics and tagging fic promo accs who will repost your promos helps circulate your fics. The more eyes on your fics, the more readers who will love them (yay) and sometimes those readers will reach out to you directly to tell you so and chat about your work(s). I'm pretty reserved about my circle, but many of the friendships and acquaintance-ships I have formed through receiving such DMs. Also, post other things not related to your fics; this could help increase odds of engagement over additional shared interest. What other groups do you like? What music, movies, shows, dramas, books do you like? Participate in those little trends that go around every now and then, like right now the dead dove tier list is a thing. These things help show your personal interests too. There are also discord servers, but I'm actively terrified of discord, so i can't really touch on that

All of this will help you out, but being super active and involved on twt is #1. Thanks for your question, and I hope you finds lots of good writer friends!! <3