i would advise, step by step approach. a straight "hi" approach
might just scare her away.
Day 1: the next time you see her, play the "eye flirting" game
with her. steal glances, if possible long glances. she will
definitely feel that she's being watched and when she look at you,
look away. repeat action of stealing glances and when she look at
you, look away. do that for the whole journey if possible.
Day 2: start with "eye flirting" again, try not to meet
her eyes for a few times but when you are ready, when she look
at you, look back... don't give her that i'm going to eat you up
alive stare please... she might press the emergency button. if you
are daring, give her a hand gesture indicating "hi". if she likes
you, she will respond. if she don't respond, you can kiss this gal
goodbye. but even after she gives you a hand gesture, do not walk
up to her yet... leave it to Day 3... you need preparation cos' you
may not look your best.
If postive response, continue to Day 3 if not, go to another
cabin when you see her again. if ever meet again, give her the
non-chalent "fuk care" expression (lol)
Day 3: Please dress your best, brush your teeth and have a fresh
mint... gals hate men with bad breath unless she's your wife, tell
her "too bad, you are already mine and you have to love my bad
points". if you see her in the train, let your eyes meet and please
smile, "hi" gesture and gesture if you could approach. it's quite
easy actually after if she is okay with you approaching...
the rest depends entirely on you.