Don’t be the angry (young) man (or woman.)
Seriously, give anger up. The ROI is small. Once you learn to let it go you’ll be amazed at how good life can feel. And how much more people like you.
You may have legitimate reasons for being angry - it doesn’t matter. Have your flash of anger and then let it go.
You get one shot at this life. Enjoy it.
One other thing, never pass up a chance to “pay it forward” – if someone does you a favor & you can’t reciprocate, at some time in the future, do the good for someone else. May I give you two examples?
Years ago, when I didn’t have a car, coworkers picked me up, gave me rides to work. Years later, I was more than happy to do the same when a coworker needed help.
Also, years ago, I needed food. Someone gave me bags of groceries, for which I was very grateful. My daughter’s pregnant friend recently needed food. I was grateful to be able to fill her cupboard until she could get welfare.
Don’t ask for a favor in return…tell them to pay it forward.
Me, I have no wisdom, and therfore no advice. But I at least hope to be a conduit of the wise and their advice:
Bismark, and Lord Chesterfield
(does not include Bismarks best advice: Love is blind, friendship tries not to notice.)
Also Paula Gorski; a friend years ago who saw two friends of her’s tearing eachother apart; specifically my first wife and me, and wisely stayed out of the fray but nonetheless could not but help utter over her shoulder the best realtionship advice I’ve ever, ever heard:
**“You guys can work it out, if you want to work it out.” **
The Lord loves a workin’ man.
Don’t trust whitey.
If you catch it, see a doctor and get rid of it.
Jeeze four days and not a mention. Not even a “don’t trust whitey.” I don’t need this thread, and I don’t need you. I don’t need anything except this ashtray. And that’s it and that’s the only thing I need, is this. I don’t need this or this. Just this ashtray. And this paddle game, . . .
From our family, the “parental wisdoms” that our middle-school-aged son can recite already:
Rule one: do NOT fuck with the wildlife. (In practice, it’s used this way: an elk is standing by the street. Daddy yells, “RULE ONE!!” Son is not mauled.)
When you find you’re in a hole, stop digging.
Everything in life’s a tradeoff.
Mel Brooks’ rule of comedy: “Tragedy is when I cut my finger. Comedy is when you fall into an open sewer and die.” (Translation: when you screw up/hurt yourself, and people laugh, don’t take it personally…it’s just human nature. We sent him off to first grade with that one memorized.)
There are more, but those are the ones we reference most often.
And I certainly can attest to the wisdom of being nice to everyone, even those you are not currently trying to “butter up.” The co-worker I welcomed warmly turned out to be my new boss (unbeknownst to me); you truly never know who is talking to whom (“that was the CEO’s daughter’s babysitter?! Uh oh…”); and it just makes life entirely nicer and more civilized.
Don’t be long-winded. (Ha! Just kidding!)
I think this was the original wording of the Prime Directive on “Star Trek” before the censors got hold of it.
Most people in this thread probably don’t need this advice, but still I want to stress:
READ. Become interested in the world around you. Expirience is great, but it is only half of it. Read, become a knowledgable person on various things. Don’t do this as means to impress others, do it for yourself. There is nothing worst than when one is in the last years of one’s life one looks back at it and says: “What *do * I know?”.
Life is filled with mysteries, go ahead and find out more about them. Trust me, you will feel so much better afterwards.
Also, Stay true to your morals. Avoid lying, cheating and stealing. Yes, there may occasionaly be circumstances in which doing one of these things is “excusable”, but still, try to be a person who his firm on his/her moralities. How can you give advice if you can’t apply it to yourself?
Also, and although very cliche, be youselves. Avoid becoming another sheep in the flock. One’s identity is important, and although at first it may be hard to fit in, you will soon find friends. Good friends.
Hydrate. I know a lot of people that went half their lives never drinking enough water who were amazed at how much better they felt and how they got fewer minor illnesses once they forced themselves to start pouring more H[sub]2[/sub]O down their throats.
Don’t assume that you know everything about an experience you’ve never had. That doesn’t mean you have to do anything and everything just to get the right to speak with authority, but realize that your preconceptions don’t mean as much as actual experience.
(Those are related. Most of my friends who were chronically dehydrated assumed everyone was overstating the benefit of keeping their cells wet until they tried it themselves.)
Do what you love, love what you do.
My father taught me this. He found something that he could love to do for his living. And he did what he loved as a hobby. In everything he did in life, he found the most enjoyable aspect of it, and focused on that. He was never rich financialy, but he was the richest man I ever knew emotionaly. Even when he was going under the knife for open heart surgery. He saw it as a chance to play with some really cool medical toys. I wish I could be that uipbeat about everything. But I try.
When budgeting time for a project, asume worst case scenario. Then add fifty percent to the estimate. There are always little stupid problems that need to be trouble shot. This is true for all endevours. Including leasure time. (Ex. If you think that you can ride all of the rides at the amusment park in 4 hours, then adding large crowds to the mix means it will take 6 hours. <worse case> But if you dont add the extra 50%, then when it rains off and on all day closing and restarting rides, you don’t get a chance to ride the barrell o’ death last like you planned to. And you don’t get to your dinner reservations liked you hoped.)
2a. Prioritize. When you do get caught short on a project, know ahead of time what you can lose without adversly affecting the project. Don’t spend 25% of your time trying to fix somthing that only adds .5% quality to the finished project. (Ex. Don’t spent an hour in line for the Barrell o’ Death when you can ride four other rides on your list in the same hour.)
The stripper does not really like you.
Credit cards are not evil. They can be quite useful, in fact. However, if you can pay off your entire bill every month, do so. If you can’t, you’re spending too much.
Pay attention to your cost of living, but don’t neglect the cost of not living. I.e., while you can save quite a bit by not always buying the $5 triple mocha latte at Starbucks and not always insisting on having the newest and bestest of everything, making yourself unnecessarily miserable just to scrimp and save every possible penny is missing the point. Save so you can enjoy the future, but don’t forget to enjoy the present, as well.
Carefully considering your options and planning ahead won’t prepare you for everything, but panic won’t prepare you for anything.
When you worry about what others are thinking about you, stop and consider how little of your day is spent thinking about what others are doing.
Don’t get involved in an argument about tipping on the SDMB :D.
Seriously, some of these are good.
May I add:
-> First impressions are important, but they are not everything. It is quite often possible to change someone’s opinion of you if you work at it. There are exceptions to this of course, but try to give everyone you meet a chance or two before you dismiss them.
-> Related to the above: Never underestimate the distance that taking an interest in someone else’s passion can take you.
-> (As with TheFury, if you’re reading this you probably don’t need it): There is life outside your home town, your circle of friends and your job. A hell of a lot of it. Don’t let yourself be trapped in an unhappy rut for want of a sense of adventure.
-> It is possible to win consistently at poker, but it takes a lot of skill and the right psychology on your part. Have a suitable bankroll for the stakes you are playing at and don’t play with money you can’t afford to lose. It is a game of skill but it is still gambling!
-> If you play poker in a casino don’t be tempted by the table games or slot machines. Unless you’re lucky enough to find a crooked roulette wheel or a counting-friendly dealer, you’re playing a mug’s game.
-> (This has already been said but bears repeating:) When you start a new job, be sure to do as best you can to get on the right side of the secretary/PA/receptionist.
I’m surprised no one’s posted this yet! 
"Go placidly amid the noise and waste, and remember what comfort there may be in owning a piece thereof.
Avoid quiet and passive persons unless you are in need of sleep.
Rotate your tires.
Speak glowingly of those greater than yourself and heed well their advice, even though they be turkeys.
Know what to kiss and when.
Consider that two wrongs never make a right, but that three do.
Wherever possible, put people on hold.
Be comforted that in the face of all aridity and disillusionment, and despite the changing fortunes of time, there is always a big future in computer maintenance.
Remember the Pueblo.
Strive at all times to bend, fold, spindle and mutilate.
Know yourself. If you need help, call the FBI.
Exercise caution in your daily affairs, especially with those persons closest to you…that lemon on your left, for instance.
Be assured that a walk through the ocean of most souls would scarcely get your feet wet.
Fall not in love therefore; it will stick to your face.
Gracefully surrender the things of youth:the birds, clean air, tuna, Taiwan, and let not the sands of time get in your lunch.
Hire people with hooks.
For a good time call 606-4311; ask for “Ken.”
Take heart amid the deepening gloom that your dog is finally getting enough cheese.
And reflect that whatever misfortune may be your lot, it could only be worse in Milwaukee.
Therefore, make peace with your god whatever you conceive him to be – Hairy Thunderer or cosmic muffin.
With all its hopes, dreams, promises and urban renewal, the world continues to deteriorate.
Give up."
(from “Deteriorata”, “National Lampoon Radio Dinner,” a 1972 recording by Blue Thumb Records. Lyrics by Tony Hendra.)
Other than that, ditto most everything that most everyone has already said here.
My mother handed down to me a piece of lore known as the Duke of Wellington’s Advice. Apparently, when the Duke of Wellington was an old man he was approached by a young man who was seeing public office, and who wanted his advice. The Duke replied, “Never miss an opportunity to eat, to sleep or to pass water.”
My mother assured me that this story was absolutely true.
The advice never fails, and now all I have to do is to remind my children, when we are traveling, “Remember the Duke of Wellington’s advice,” and this is likely to be passed down generations!
Avoid cynicism, but recognize that it is natural and, to some degree, inevitable.
At the same time: If you see a razor blade, get ready to slide down it.
Dont ever set anything down temporarily on top of your car – like groceries, luggage, etc. Good chance u’ll never see it again. Made this mistake more times than I’d like to admit while traveling.
Always have a good book nearby. Always know what you’re going to read after you’re done with your current book. Always take time to read for fun.
Don’t be afraid to say, “I don’t know.” I’ve struggled with my son on this one…he’s smart, but he knows it. He has a tendency to try to bullshit his way through something to prove he’s smart. He needs to learn it’s okay to say, “I don’t know.” Then you can go find out.
Doublecheck your answer before you answer someone’s question. I’ve caught myself at work about to dash an answer off via e-mail, then I doublecheck something, and I find I’m revising my answer more often than not.
Hang around people that are smarter than you.
Your subconscious cannot take a joke. Think you can’t do something, and you won’t be able to do it.
If you can’t change the people around you, change the people around you.
If you believe you have the right to live your own life, you have to give other people the same right.
Criticize actions. Do not criticize people.There a world of difference between saying “you did a really stupid thing” and “you’re a really stupid person.”
Always and never are loaded words. Seldom use them.
Question all authority. Leftists sometimes have good ideas, and rightists sometimes have bad ones. 
Always have an escape plan.
Right: gas; left: brake.
A decent person who thinks they’re doing the right thing can and will do anything. Anything.
If you go to Alaska, bring bug repellant. And make sure it works, first.
Be nice to people who handle your food, or clean up your filth.
( Corollary to the above, don’t be a jerk to robot slaves. You never know…)
Bad luck is generated at a directly proportional rate to the size, expense, and complexity of the wedding.
It’s a cruel irony, but some of the quickest, most painless ways to die are also the most gruesome.
Music makes the scene. Even more than special effects, or acting.
You can achieve surprisingly good-looking results by applying detailed textures to fairly low-poly objects.
Take the full course of medication, even when you start feeling better. Seriously.
Every death, even the cruellest death
drowns in the total indifference of Nature.
Nature herself would watch unmoved
If we destroyed the entire human race
—Marquis de Sade
“If somebody’s trying to shut you up, sing louder and, if possible, better.”—Salman Rushdie
“If it’s stupid and it works, it’s not stupid”—Russian adage