Chat about the weather - boring but a good ice breaker
Start with Hi, how are you....Honestly. A simple opener such as that gets the ball rolling
Yes. Decide what your personal opinion is concerning current cultural situations related to the demographic of your strangers, and then put it out there. Unless it's dumb. Or if you have no opinion on it, ask others is anyone else has an opinion on it, whatever it is.
Hi, my name is... , would You like a chat?
Spill your drink on the stranger and say sorry... or simply say "Yo, what's up", or if you like to sound more kind "Hi, how's it going?" or "Hello sir/my lady, how are you faring this fine evening/morning?" or simply "hi"
I have seen you somewhere...
Umm, Er, Well, I Don't Remember..But Nice to Meet You, Can We Talk About My Latest Obsession? :D