While some people grow up with public transportation, the routes and schedules as familiar and regular to them as family names and birthdays, others grow up scared of it. For these people, the words 'bus' and 'subway' may conjure up frightening images of young men and women in ties and pantsuits on their way to their downtown office job getting shanked by urban youth with low-slung ratty jeans and a propensity for curse words. Perhaps in your minds eye all you can see are germs crawling all over the worn plastic seats, gum decorating all flat surfaces like some sort of low-culture art piece. If this sounds like you, then please take the time to let this sink in: public transportation is not what you think it is. Sure, there are of course the exceptions, and maybe riding through a bad part of town at 1:00 am isn't a particularly advisable decision, but overall public transport vehicles are here for you, the public, and most people riding it are just your average person trying to get from point A to point B. No ulterior motive, just a convenient and cheap way to get where they need to go. Although there is often a stigma that promotes the connection of public transportation users with members of a lower class. This is, in most cases, not the truth. For people that live and work in a city, owning a car is often considered unnecessary, even if they can afford it. Hence, more often than not, user's reasons for taking public transportation has nothing to do with their financial situation.
Furthermore, the people you do ride the transportation with are fascinating, and have so many cool things to share about themselves and their lives with you if you have the patience to listen. Even if it's just overhearing conversations, or watching the dynamic between a mother and her daughter, there is so much you can learn about people that can really open your mind to different perspectives and give you a taste of what it might be like to be in someone else's shoes. Although some people hate buses and such for this reason, I find it to be one of the chief reasons for taking it. It might sound sappy, but looking around and thinking about how each person has their own story to tell with complex webs of people and events trailing behind and ahead of them is one of the most effective ways of gaining some perspective on your place in the world.
If you're worried about the hygiene of these systems, I won't lie to you: things can go as well as you'd expect if you hop on at midnight and there are a crowd of drunken people sharing your car. However, do not assume that because somebody barfed once, it'll happen again. Instead, just think of the cool story you have to tell now. Public transportation is made possible through your taxes and other government funds, so if the bus isn't as spiffy as you'd like, then you can have a say in what should be changed.
As for bus drivers themselves, the etiquette here is pretty basic: if you're polite and friendly to them, they will (usually) be polite and friendly back. Don't be afraid to ask for directions, either: they drive this route all day everyday, so chances are they'll know how to get you to where you want to go.
The moral of the story is, even if it's just once, give your local bus/metro/train system a try. Cast away those stereotypes and fears, jump on, and who knows? You might even ending up liking it.