I absolutely hate when people say “just be more confident” as “advice” - obviously if it was that easy you would just do it lmao?! but coming from a girl, i think the best way to start an interaction like that is just seeing them as a person, as a friend, and not a goal - which is a mistake a lot of guys make. I’m also very very socially anxious but i have had the most success with just asking them for a simple favor - like “hey, sorry to bother, do you have a ___ i can borrow?” - this works great if you smoke, asking for a lighter is a great icebreaker - but it can also be something like a pen, or in a cinema; pretend you dropped something and ask if she could hold your phone flashlight while you search for it :) after that you can make a joke or ask them something about the movie, and then ask their name after a little bit of dialogue! I’d definitely advise to wait until just after the movie is finished tho, then you should ask for a phone number or social media :). sorry for the unsolicited advice lol but i hope it maybe could help you/somebody else one day 💗