Paramedic

When paramedics arrive at a car crash or similar accident, they very, very rarely announce any casualties at the scene—almost all deceased will be pronounced “dead on arrival” at the hospital. This is because it involves about 10 times more paperwork to announce someone dead right in situ than it does to say they expired in the ambulance on the way to the hospital.

Nurse

Patients will occasionally pretend to be unconscious. A surefire way to find them out is to pick up their hand, hold it above their face, and let go. If they smack themselves, they’re most likely unconscious; if not, they’re faking.

Mechanic

If you have to change a light bulb where the glass is broken, you can press a potato into the metal base to unscrew the remains of the bulb from the fixture.

Lounge Pianist

Never agree to Christmas sing-alongs if there is alcohol involved. Your singer will only remember the first two lines of his favorite tunes, or you’ll waste a half-hour on a drawn-out, stumbling, “12 Days of Christmas.” The singer will be forgiven when he sobers up, but you’ll look unprofessional.

Landscape Architect

You will often have to create a large presentation for clients, and will spend hours coloring in landscape illustrations with markers. But if you say the drawings are “rendered” rather than “colored,” you can charge four times as much.

Cartographer

Mapmakers will often use “copyright traps,” bits of information in their maps that are purposefully wrong. They might label a body of water “Lake Strongbad,” for instance, and then examine the next editions of competitors’ maps to see if the incorrect information makes an appearance.

Auto Mechanic

Always put copper grease on the battery terminals after servicing a car. The performance benefit is negligible, but when customers look under the hood they will immediately see that something’s changed and thus feel happy to pay you.