If you haven’t already, I recommend checking out this pinned post: WrA Information & Directories (Guilds | Communities | Events) (Click the 
's to expand the sections to get lists of guilds and what they’re all about, Discord servers, and other resources!)
For me personally, it seems like the best way to make connections has been to join some of the Discord servers for WRA RP events, and attend announced events to mingle with people there! A lot of the stuff is neutral-faction, but you’ll surely meet plenty of people who play on Horde side in these places!
I’m also a very shy person by nature, but what’s helped me a lot is to be more bold about putting myself out there and approaching to start a conversation first with a friendly hello! It can be intimidating, but most people will be happy that you contacted them because they’re also looking for new friends/guild recruits/community members.
Many of the Discords also have general chats where you can casually hang out with people who attend these events, and easily stay in touch with folks you come across if you’re uncomfortable with asking for Battletags before you get to know somebody.
Making long-lasting connections is all about routine! If you ever come across someone you enjoyed hanging out with in the game, see if they’d like to follow up on it with future RP, questing, mythics, etc. on a day that’s convenient for both of you. Try to make it a once a week/bi-weekly/monthly thing if you can! The consistency will help make it easy, and it’ll give you things to look forward to throughout the month.
My schedule’s pretty unpredictable for the time being, so it’s been hard for me to commit to consistent RP routines or make a whole lot of solid plans throughout the week. However, if you ever see a mantid named Nazgo’rak hanging around at an event, you’re welcome to come RP with me anytime!
Also, welcome to the server! 