Screwing up takes less time than doing things right, but fixing a screwup takes longer than doing things right. As for the time of doing both, you do the math. - Can’t remember who it was, one of my uncles I think
Always read any document before signing it. If someone says “just sign!”, they’re your enemy. - Dad
Contracts don’t need to be on paper to be valid. Your word is your contract; you may not always be able to find the right words, but do your best to say what you mean. - Dad
Money = Mobility.
Petty not.
life is too short to worry it away 
No one on their deathbed ever said “I wish I’d spent more time at the office.”
A variant of this was a really good piece of advice I got at my last job, while complaining to a friendly VP about how hard I was working.
-D/a
When I was a teenager arguing with my Mom, my Dad told me:
“Sometimes you have to decide if you want to be right, or do you want to be happy.”
Someone else (It would require more explaining that I care to) told me:
“Nobody MAKES you mad except you. Anyone else, you are just choosing to react to them with anger.”
Think before you act; to move right and slowly is better than fast and wrong.
Things can be undone, but they can’t be unsaid.
A man’s greatest measure is what he does when nobody’s watching.
If you don’t, someone else will.
Nobody likes the truth; tell people what they want to hear and what you want them to hear.
Opportunity is the death of morality; an unlocked door makes a thief out of anyone.
All violence is to the death. If you’re prepared to throw a punch, be prepared to kill.
EDIT: And the most important one of all! The only one I got from my late papa.
Nothing worthwhile has ever been accomplished, at any time by any person, except in the deadest calm and introspection. The moment you lose your cool, you lose it all.
I work in IT.
Best advice - Never attribute something to malicious intent which can more easily be attributed to stupidity.
One more (said by my favorite Computer Science prof):
“If brute force doesn’t work, you’re not using enough”
The most important I think I’ve heard is:
“If you don’t understand something, say so. Someone will teach you.”
This is so true. It might look like people are out to get you, and doing their damnedest to make your life miserable, but they are probably just Mr. Magoo-ing their way through their lives, completely oblivious to how they are affecting other people.
Get/eat Apple.
Don’t let the negatives cancel out the positives.
“Don’t believe the hype.”
If your foot hurts, stop and put a piece of moleskin on it before you wear a damn hole in yourself.
Have a good time all the time. That’s my philosophy, Marty.
I got several very important bits of advice in one session:
I had to use all three on one jump and walked away from it.
So true.