There are some rules that everyone should follow when the board any form of public transportation. Unfortunately, much of the unwashed (and unfortunately, I mean this literally) masses don't seem to understand.
So, again, I am here before you to teach you some rules that you should have been taught many years ago by your parents. (You know, those people who sat you in front of the TV every day of your infant life? Yea, them.)
First things first. If you're going to be riding any form of mass transit, or going to be in any public location of any kind, really, Please, please, please, please, please take a shower. If you smell, take a walk instead. I understand if someone who has a hard labouring job of garbageman, or carpenter gets on the bus at the end of the day to go home, they're going to smell. But you know what? You can tell those people a mile away. Generally, they're still wearing their belt, or at least look like the kind of person that had a long day of real work behind them. The people I'm talking about are easy to spot: greasy hair due to being unshowered for far too long, a spaghetti stain on their t-shirt, and the wretched stench emnating from their body.
The fact that you're on a bus does not increase the required volume for speaking into your cell phone, or to the people beside you has not been increased by 20dB. As a matter of fact, speaking at a normal volume will still allow the person on the other end of the phone, or beside you to hear what you're saying. This especially applies to those of you speaking languages that are not native to the place you're riding the bus. It's moderately rude to scream into your phone in Polish when the population of the bus is mainly English. Why? Because it harbours this feeling of contempt in the others on the bus around you. How the hell do they know that you're not talking about how ugly they are? (Maybe you are!)
You see the sign on the bus that says, "please exit at the back?" Follow it please. Unless you're disabled and in a wheelchair and require the front door, get off at the back so those boarding the bus don't have to stand there while your stupid ass goes the wrong way, mmk?
Plan your route ahead of time. Standing there at the bus door -- or even worse, getting on the bus, and asking the bus driver -- where the bus goes, and what roads he takes, and how he gets there is wasting everyone's time. Ask others at the bus stop around you before the bus arrives, chances are, they aren't as stupid as you, and they know where the bus goes beforehand.
Have the right amount of money/tickets/your bus pass IN YOUR HAND before you board the bus. Holding up other people, and/or obstructing the bus driver's view while you rummage through your backpack/purse/pockets is stupid. You don't sit on the can, start shitting, and then remove your pants, do you?
If the person next to you is reading, or clearly uninterested in you, don't spark up conversation. If they make eye contact, or if they're looking around, perhaps you can say a few words, and pay attention to their response to gauge whether or not they're interested in conversation. If their response is a "yea", "ok", "yup", and nothing more, stop talking. They don't want to talk to you. Don't take it personally either, there's a million reasons why they might not.