Off late I have seen lot of girls that I see in daily life (eg at common activities,gym ,friend of friends ) are on okcupid.I havent spoken directly to them in real life .How can I utilize this information that I know they're on okc and possibly looking for a partner? I tried to just message a girl who I see at a common activity (but in a totally different group) that 'Hey dont you go for ____..right'.She had seen me too . No response.She visits my profile though.Now in retrospect it might have not been the best opener or she just didnt like me/my profile.That's fine.

Today I just noticed that a girl i see at the gym is on okc.I dont want to mess this up.So how do I go about this? Should I mention the fact that I see them in the gym on okc message/never mention about okc?Similar experiences anyone?

tldr; I see a girl at the gym.Dont know her.Found her on okc.How do i proceed using this information to my benefit.