So there you are, you've got a pretty bike, your gear is on and you are ready to go! Unfortunately, no one ever bothered to tell you how to comport yourself while riding. Here's what you need to know.
If you can safely stop to check on a motorcyclist who pulled off the road, do so. Even if you can't quite handle "righty-tighty, lefty-loosey," you might be able to lend a cell phone, tools, water, gum, or just a bit of moral support. Of course, only stop if you can do so safely. If you have to immediately cut across three lanes of traffic and come to a screeching stop, you'll be excused for not stopping.
Do not pass another motorcyclist in the same lane unless he/she indicates that you should. Seriously, passing in the same lane is just a jerk-ass move. If the rider you're passing didn't notice you, he/she is going to be startled when you fly by three feet away from him. It's not just rude, it's unsafe - how can you be sure the other rider wasn't planning to shift to the other side of the lane? Unless you get waved past (I do this all the time if I'm holding someone up and traffic is tight), don't pass in the same lane.
One exception to that rule - in the twisties, if the other rider is hugging the right side of the road and going slowly, you'll be excused for passing in the same lane if you do so as safely as you can.
Wave when you can, and return greetings at stoplights. What? Are you such a bad-ass that you can't even say good morning in return? Don't just stare like you're too tough for such things. Life is rough enough, make it a little smoother by acknowledging a fellow traveller in a small way. Sure, sometimes you just can't wave because you didn't see the other person in time, or it's not safe to do so, or your hands are full of clutch and throttle. It's OK. Just do it when you can.