It is one of the best place for gaming on chicks. All you need is cojones.

Do you have game? If the answer is yes, do it if no, start having it. Go and say hi. You should have info about this chick in order to not speak bulshitting. Add her to facebook, make research and find common speakable interesting points, such as musik, moves, books whatever. Just speak, you have nothing to lose so do it.

my only suggestion is be prepared for huge bitch shields.
people on the bus are often crazy. literally. they are schizophrenic. girls know this so they will do whatever they can to make sure nobody talks to them.
be prepared for her to pretend she didn't hear you the first 3 times.
be prepared for one-word answers
i suppose not looking homeless helps (dress sharp)
here is the perfect opener that you asked for: "Hi." wait for her to say hi back. then say "how are you?"

Bart, please dont give advice because you're an extreme case and your life and experiences wouldnt apply to most guys.

Bus, planes, trains, whatever...an attractive guy is an attractive guy. A girl doesnt care where she meets a guy she finds attractive. If you can approach directly at the bar and get success, you can approach directly in a bus. If girls are ignoring you on the bus, odds are they're ignoring you everywhere else. So OP, if you can approach anywhere else and do fine, youll be ok. If you get rejected everywhere, you have shit to get handled.

neo,
what do you mean I am an extreme case? what do you know about my life experiences?
and i did not discourage the op from approaching. I was just saying he should be prepared for bitch shields, meaning keep pushing even if the girl acts bitchy because bitchiness is expected on the bus.