use a longer lens from a distance..
Do like some people said, be like a stalker.. be warned u might be get whacked.. remember the news? someone kena whacked coz he was taking someone's gf photos.. Dun be mistaken for that kind of person..
bring ur camera wherever you go, and once ur frens get used to u having a camera everywhere u go, its makes it much easier to take photos of then being in a relaxed position..
coz today, my fren ask me, "do u take ur camera everywhere u go?"
And i said, "mini project, 365 days, 1 shot a day"
then they will go like, "ooh.."
and they will get the idea, and they will be relaxed whenever u are arnd with a camera as u already told them why u bring a camera arnd..