From my Grandpa B. : "Never put your fingers where you wouldn't put your face!"
From Dale S., an old-time convict who had been a high-dollar burglar in D.C. many years ago, on the subject of tattoos: "A tattoo ain't nothin' but another set of fingerprints that makes it easier for the cops to grab you up, or for your family to identify your corpse."
From "Tightshirt", a Lieutenant I worked with in corrections: "Retire as soon as you are eligible to. You should still be healthy enough and sane enough to pursue another career if you want to."
From myself as a shift Captain to new Correctional Officer trainees: "Working in corrections can be good experience for a young person, if you know when to quit!"
From Roger G., retired FBI agent and owner of the Private Investigator company where I worked for a couple of years, on the subject of long surveillances: "Never miss an opportunity to take a leak. Go when you can, not when you have to."