Puppy Training?

What are some important things to know when training your puppy? I just got a puppy two days ago and he is about 5 months old. He is already house broken and pretty well behaved. We are going to start obidience school very soon, but until then, what are some important things he should know. Just like easy things like how to not bark at strangers and how can I enforce his good behavior and try to prevent him from misbehaving. Best answer gets 10 points!