Some day Heather will have her own website dedicated entirely to this matter, but for now, here's a page on it.

The Do's and Don'ts of Bus Travel:
Do get to the bus stop at least 5 minutes before the bus is due. This way, you will be able to get a place up the front of the queue*, and a better chance of the seat of your choice.
Do try to get one of those tickets that lasts several bus rides - it'll save you money, and you can get onto the bus faster (and thus, again, have a better chance at the seat of your choice).
Do have your money and concession card ready.
Do have the right change so that you can save time (your own time, that of the bus driver, and that of everyone else in the queue behind you.)
Do be polite** to the bus driver when you buy your ticket, and thank them when you get off (if exiting via the front doors).
Do let the odd less mobile (old and frail, people carrying loads of stuff, etc) person in front of you if they're next to you in the line from time to time (ie, you don't have to let everyone in front of you, but if they got to the bus stop before you, but ended up next to you in the line, you may as well let them go in front rather than behind you).
Do take the window seat. That way the seat next to you is available for another passanger.
If you have to stand, move to the back of the bus first, so that the people following you have room to stand too (rather than tripping over each other and getting tangles up each time the bus turns a corner or stop). After all, there is a supposed limit to standing passangers, so you may as well make the ride as comfortable as possible.
Do be aware of whether the person in the window seat (supposing that you're in the isle seat) appears to be about to get off the bus before your stop, so that you can let them out in time to get off the bus easily.
Do try to keep your belongings to yourself. The person next to you doesn't want your library books in their lap, or your hair on their shoulder.
Do try to be patient. Not everyone is as great at all this than you. There will always be someone who has to drop their change on the floor when they try to buy a ticket.
Don't smoke in the middle of the crowd at the front of the queue for the bus. It's really offensive, and unhealthy. Non-smokers like to be able to have an equal chance of a good seat on the bus, without sacrificing their health for your disgusting habits.
Don't fart on the bus. That's just gross. Wait until you get off (and out of the crowd who just got off the bus with you!).
Don't stand right in front of the time-table at the bus stop. People want to be able to see it.
Don't push in front of people when the bus arrives. If you weren't waiting up the front of the queue, don't take the place of someone else who was*.
Don't sit in the seats at the very front - they're for elderly and less mobile passengers.
Don't try to buy a ticket with a $50 note. That's really inconvenient to the bus driver who has to find the change for your 80c ticket, and for everyone else waiting in the line for a ticket, while all the people with the pre-paid ones get all the seats.
Don't take the isle seat if the window seat is free. If you paid for one ticket, then you paid for one seat. Your fellow passengers will not appreciate it when there's an extra seat that you're keeping to yourself.
Don't put your belongings on the seat next to you. That's another seat that a paying passenger is missing out on.
Don't sit next to someone when there are other double seats free. (ie, when someone has a window seat, don't go and sit next to them in the isle seat if there's a set of window and isle seats both free elsewhere).
Don't sit next to someone who has a lot of luggage with them when you can sit elsewhere. People shouldn't need to unnecessarily go out of their way to keep their stuff out of your way if you could be sitting somewhere else.
Don't stand in the way of those who are trying to exit the bus.
Don't listen to music too loudly on your discman. Nobody else wants to hear your bad musical taste.
Don't talk loudly on your mobile phone. Your conversations really aren't that interesting.

*Just because you're waiting up the front of the crowd doesn't mean you'll get a good spot in the queue. Most people are morons and will take any chance they can get to push in front of you. Especially when you are, for whatever reason, less mobile. People are bad. Remember that.
**If the bus driver is rude to you, you shouldn't be rude back (unless they really deserve it), but you don't need to be as polite to them either. 

More Do's and Don'ts coming soon...

Very Important: You must never... Don't even THINK of getting in the line for those prepaid electronic ticket things, only to get to the front and then push in front of whoever is at the front of the ticket-buying line with your $10 note. EVER!

Bus Etiquette FAQ

I find it really offensive when I'm waiting in the queue for the bus, and someone is smoking. What should I do?
Heather's Solution: Water pistols come in compact sizes for low prices these days.

I don't know how much the tickets are, so I can't bring the exact change.
Heather's Solution: If you're really worried about this, I suggest you find another mode of transport.

I got a bus yesterday, but the bus driver was really evil. He didn't want to let me on because he was convinced that I was a school kid, and refused to let school kids on the bus. I kept holding out my uni card and saying I was a uni student. He just wouldn't believe me, and tried to close the doors on me. Should I have continued to be polite?
Heather's Solution: No, do what I did when that happened to me: Yell at him. Growl "I SAID <insert name of university> UNI!!!" and stick the card right in his face. The other passengers will be on your side.

Sometimes I have to catch a bus whilst carrying lots of heavy musical equipment/library books, etc. I wait at the front of the crowd, but when the bus arrives, everyone pushes in front of me because I can't stop them. What am I meant to do? It's not fair that I get their first, and really need a seat when I'm carrying that much stuff.
Heather's Solution : Beat them up. If you've got your hands free, which, unfortunately you don't. Sadly, there is no easy solution for this one. (I'd know!). Maybe dress in a manner that makes you look as threatening as possible. Lotsa spikes and stuff. Or hit them with whatever you're carrying, as long as it's not fragile. After all, it's their fault for pushing past you like that.

What do I do when I have to stand on the bus, and the person behind me won't move to the back, and thus is wasting space that we could all do with?
Heather's Solution: Wait until the bus stops, and "accidentally" crash into them. Maybe then they'll move to the back.

There are no seats left, except for a window seat, which a rude middle-aged woman is hiding while she sits in the isle seat. What should I do?
Heather's Solution: So far I've never attempted anything, because I just assume that if someone is so rude as to take a seat that another paying passenger deserves, then they're an asshole who probably won't give up the seat even when someone asks for it. However, I recently saw a girl ask an old man to move into the window seat so that she could sit down, and that worked out fine.

There are no seats left, except for an isle seat, which a rude middle-aged woman has put her bag on. What do I do?
Heather's Solution: Politely ask her if her bag has a ticket. If it doesn't, maybe you could sit there...

Sometimes I have a lot to carry on the bus with me. When there are other free seats, people still tend to sit next to me, which makes it hard to travel with so much stuff. What should I do?
Heather's Solution: You could "accidentally" drop it on them, or hit them with it. And to prevent this in the future, try dressing in a threatening manner, or don't wear deodorant.

The dude sitting in front of me is listening to music really loudly on his walkman. It's really annoying. What should I do?
Heather's Solution: Get a pair of scissors, and cut the headphone cord. This is not only making the bus a more pleasant environment audially; but you are also preventing the person in question from further damage to his ears.

The girl sitting in front of me is talking on her mobile phone really loudly. What should I do?
Heather's Solution: Take the phone out of her hand, tell the person she's talking to that you're awfuly sorry that they've had to endure such loud and boring conversation, and hang up. You may or may not also through the phone out the window, depending on whether the bus has opening windows...