Hello, you can always ask what time it is [just hide your watch first] After you thank the stranger you can say, 'What a beautiful watch. I have just lost mine. Where can I buy one like yours?' Then you can move onto other topics like the weather, the crowded train etc. Sometimes when you just say hi, the other person says hi back & nothing else happens.

Hi Aurora, I agree with Harregarre. Just be confidence on yourself, than try to communicate. People will quite understand, that English isn't your mother tounge. Eventhough English is the worldwide language. Don't be scared to start! You can do it

The Aussie way "Hi mate", "g'day mate". Or the universal "Hello, how are you today"...

Eh, just say hi and start talking? :P