A few that I have been influenced by over the years:
People will believe anything you say if you tell them that Benjamin Franklin said it first.
Never attribute to malice anything that is more easily explained by stupidity.
99% of all human wisdom consists of a willingness to keep your mouth shut. – Albert Einstein
You are entitled to your own opinion. You are not entitled to your own facts. – Carl Sagan
Don't let yesterday use up too much of today.
Opportunity is missed by most people because it arrives in overalls and looks like work. – Thomas Edison
When you are going through Hell, keep going. – Winston Churchill
All generalizations are false, including this one. – Otto Koppen
Pick your battles big enough to matter, small enough to win. – Jonathan Kozol
There is always an easy solution to every human problem–neat, plausible and wrong. – H. L. Mencken
Panic is what happens when you run out of training. – Sandy Stevens
With all your getting, get understanding. – Proverbs 4:7