It's the "no pressure" principle. It's easy to clam up and get so uptight around girls, but what i do is i loop my mind on positive thoughts (instead of the horrible negative nasty demon thoughts that, during my worst days of psychosis and depression, resulted in me being antisocial for months at a time and just getting stoned, sort of like a sociopathic Sherlock Holmes when he's working on a case), and also i REMIND myself that i have HAD sex and HAVE been with girls (i'm a pothead, and the problem with that is you forget things). So the approach anxiety itself is really stupid. If she politely rejects you, smile and have a nice day, no problem. If she's a bitch about it, or it's so crass it's obvious it's a shit test, then play the agree and amplify or even just the childish mimicry card. Like if she goes "you're so short", go "IM SO SHORT" and pull a weird crazy face (like a gurn) and look at her. if you're lucky, that is when she will do that thing girls do when they laugh about you to their friend(s) with them and go "oh mah GAW-hawd" and then u know u're in and u might get some puss2395sdisdusdksakasjaskaa!! !! !!!! ( ͡° ͜ʖ ͡°)

Other things that seem to help are smiling and just remembering to be in the moment. I think you should talk to the girl, and then if you want to try to turn it into a pickup you can, or it can just be talking. I'm in college, and now I have started coming out of my shell slowly and talking to girls more. It's the method and practice itself that matters

I guess I'd like to hear from the guys with social anxiety, depression, etc. Mental illness does not make this easier, but I am of the rare belief that with the exception of batshit crazy folks, many mental illnesses can be helped with therapeutic action in your everyday life