“Take good care of yourself.”
When you aren’t; it’s lifesaving advice. When you already are; it’s still pretty good advice.
I got the advice from the director of Psychiatry at an inpatient hospital.
Some of her other good, but simple bits of advice were put in the form of questions.
“If everything was not as bad as it is now, what would be different?”
“Who should do that?”
“When should you start?”
Very wise lady. Smart too.
Tris
“Things will work out, though maybe not in the way you expect them to.” - Mom
“An adventure is an inconvenience rightly considered.” - G. K. Chesterton
“Feel guilty if and only if you have done something wrong.” - Mom
“Sticks and stones can break my bones, but words will never hurt me.” - old proverb
“You are not smarter than everybody else.” - Mom
“Those who deliver good performance will succeed, those who deliver good excuses for poor performance will fail.” - what I tell to incoming freshmen
The bit from airplane safety instructions about putting your oxygen mask on first and then helping other people. It applies all the damn time. If you don’t make sure you are ok/functioning/safe -physically, emotionally, whatever - it makes it that much harder to help anyone else.
“Be Excellent to Each Other”
The Jerk
From my late mother:
“If you’re in a nightclub or at a party, ALWAYS make sure you know where the exit(s) are. If you need to get out in a hurry for any reason (fire, fistfight, etc.), you can’t waste time looking for exits.”
I keep reading this as “Get rid of your nuts.” :eek: 
One of my favourites was, “Just because you can, doesn’t mean you should.” I think the turning point in maturing comes when you really grok this saying.
One thing I learned while delivery driving - never go back for something when you’re there right now. You always think you don’t have time now, and you’ll come back to stuff, but life seems to get in the way and you wish you’d done it when it was convenient.
The art of good conversation is to ask questions.
My mother told me this when I was 16 and wanted advice on how to deal with girls. Boy, was she right.
From Practical Wisdom for Perilous Times: Selected Maxims of Baltasar Gracian:
“Sleep is the silent partner” - worked for me in the past when I have a problem to solve. Sleep on it.
“Think twice. Speak once.” and “There is always time to add a word, never to take one away.” (or something like that)
I don’t remember where I got this, but it was in the context of learning a musical instrument.
Don’t practice the mistakes (go slow, get it right).
And I don’t know if this counts as advice.
An amateur practices until he gets it right. A professional practices until he can’t get it wrong.
I like those, Small Clanger! I’m going to pass them along to my daughter, who is learning to play guitar. As we all know, teenagers just love a piece of good advice. 
Oh, I thought of another one that I used especially in learning to drive, but it works well in lots of situations; when you’re developing habits, it’s as easy to develop good ones as bad ones. In other words, if you don’t take shortcuts while learning something, you’ll develop the habit of doing it the right way.
On athletics training, as told by my martial arts instructor:
“I’m teaching you to do this correctly now when you’re twenty, so that you can still do this when you’re sixty. Otherwise you’re wasting my time.”
I know so many people who recreationally damaged their bodies permanently by their 30’s and 40’s, almost all by irresponsible training or poor technique.
Similarly from my father:
“Don’t play high school football, it’s not worth having bad knees for the rest of your life. The band gets cheerleader tail also.”
My favorite employer of all time, who routinely interrupted meetings to take calls from angry customers &/or angry vendors, much to the vexation of other managers in the company:
“Beck, every interaction is an opportunity”
Because he did this, and because he was effective at making those interractions into opportunities to shine, such calls tapered off drastically as his management went on. I’ve never known another employer who relished the opportunity to turn a potentially flamable situation into a “friendship for life” like this dear man, whose day was never “troubled by interruptions”. He built an amazing empire with this philosophy, one that I am sorry to this day that I ever left.
My father: ‘Less haste, more speed’.
If someone offers you a breathmint, take it.
From my dad:
“You plan on A, B, or C. You usually get D, E, or F.”
Integrity is shown by what you do when nobody’s looking.