I am a geeky ~20 years old average looking guy and usually turn insanely stupid, like saying something and regretting it a couple of seconds later, during smalltalk / flirting with a stranger.

During my school years I had plenty of women approach me, but I always declined, since I didn't want any of that insincere "it's just a school relationship" bullshit.

Now I have the issue, that I don't know any gals with simular interests (the one I wanted to ask out after school moved for uni) and have the options of either chatting in a geek dating site, where I risk meeting some real weirdos or trying to approach ppl during eg. conventions, where I risk being a creep.

Advice on how to approach the situation and maybe a method for training to collect myself during chitchat would be greatly appreciated :)