When It wasn't intuitive to me or for the other side, I used some sneaky ways/tricks: Asking them if they're from here? if yes - ask a favor. and then ask some other questions about related stuff... if no - "then where are you from?" "and what are you fucking doing here?"

complementing them - on anything.

Don't care. you'll never meet them again (if something goes wrong) so if you want something, ask for it. if you have something stupid to say, say it, it's better than nothing.

I did it at the train, bus, street, hostel.

it seems that everyone in their headphones and doesn't want to talk, but people actually like to discover, to learn, to joke. It's just a mask.