(In no particular order)
1. Focus on yourself, instead of other people. If all the world's problems are somebody else's doing, your self-image probably isn't too realistic. Everybody has a ton of advice that they ignore themselves. While it may not be as effective as screaming and waving a .50 cal., leading by example has the advantage of being an effort to lead by example.
2. Each person's life is unique, and unless you get hit by a train, odds are the entirety of your existence will flash before your eyes when you die. You don't want this to go by too quickly, you don't want to look at your own life and not be able to tell it from the guy's two cubes down, and you don't want your last thought to be "Wow, I really WAS a prick!"
3. Roughly half of everything you're told will be wrong. If you really try, you might remember to ask "Why" each time you're told something. "Why" is the most important question you can ask, not just because it will cut down on the overall level of misinformation, but because there's a real percentage in being able to bullshit people and it relies completely on people doing what they're told.
4. The only thing worse than entropy is solipsism. Yes, the universe around you is decaying at rates just as fast or faster than you yourself and if its going to make you a nihilist, the ultimate form of nihilism is to void yourself out. But if you've just gotta stick around to see how the movie ends, then the last thing you want is for somebody to try and shoehorn you into their reality picture. Its a two-way street.
If you assume your view of existence is the same as everyone else's, you're going to end up trying to shoehorn somebody else into a space they don't fit. Nobody is so different from you that they'll simply do things for no reason at all, and nobody is so similar that they'll do things for the same reasons you do.
The importance of walking a mile in someone else's shoes is not just because its the only way one can reasonably hope anyone else will return the favor, but because its impossible to understand one's self or anyone else outside that contrast.
5) There are a million and one ways to waste your life, and one of the easiest is to buy into someone's off the rack value system. Being good is not difficult, in fact, it comes fairly naturally; if it seems impossible then its probably because somebody's conned you into thinking that if you're not perfect, its because you're inherently bad. This is a good way to waste your life enriching the hypocritical, since real gurus tend to place enormous value on avoiding having anyone mistake them for a guru.
If you can't accept the values that you have, you'll wind up living in denial of your own behavior and hating yourself for falling short of a standard you weren't ever capable of or interested in in the first place. Make mistakes, learn from them, and move on.
6) There are real reasons to live in fear; too many do so because that's what they think they're supposed to do. If you lived your life in complete obedience to someone else, you are still trusting your judgment enough to see some wisdom in acknowledging their authority. If you can't bridge the gap between your judgment and anyone else's, other people will live your life for you. Think for yourself because you HAVE to, and nothing will come of it until you can.
7) No one can give you value. The pat on the head, the little stroke that comes with a compliment or a trophy is absolutely meaningless if you think you got it by fraud. The only time you will ever feel worthwhile is when you are certain that you deserve to feel worthwhile and if you don't, no one can tell you otherwise. And when you do feel that, yourself, the rest of the world can FO&D if they don't agree.
Not everything fits into a numbered list, and while sitting around and comparing notes with other people surely ranks among the best experiences in life, too much of it can be a distraction from making a genuine effort to figure it all out.
And that you have to do on your own.
But that's also the very best thing that there is*.
*Besides driving one's enemies before them and hearing the lamentations of their significant others, of course. YMMV.