idk how to flirt BUT what I can imagine is the not SHY shy one starting with small greetings at first, since they're supposed to be strangers. and it imposes a routine where the shy shy kinda knows they're on a hello basis, small talks and all. then it will be "Hi, I like your hair today" instead of just "hi"... and from then on the flirting increases ? "Oh seeing you every morning is the highlight of my day" and then the shy shy starts to try flirting as well...
honestly idk what I'm writing 😣 hope it helped a little 🤏 (even 0.000001%)