There is way to many to list...learning the hard way seems to be the only way I learn
Don't believe everything that is told to you.
That no matter how hard and carefully you plan for all contingencies, you can still lose everything you care about, and in a really short period of time.
Always wear a motorcycle helmet. Especially when making love.
Most of them.
There are people who don't know loyalty or morality or simply how to be humans.
That people will do things to you that you'd have never done to them in a million years.
Don't be rude.
Basically all of them.