As a very low hour Sport Pilot, I've learned a few things that I have taken to heart:
If I wouldn't pull a cart for 18 on the golf course I won't fly over it.
There are no missed approaches, just practice ones, and they're free.
Always factor practice approaches in your fuel calculations.
Whenever two windsocks shall be placed on opposite ends of a runway they will disagree.
Smoke from trash fires trump windsocks.
In Alabama in the summer, remember that reported gusting is to be applied vertically as well as horizontally.
The only difference between a touch-and-go and a bounce-and-go on a creative wheel landing is entertainment value for the people watching.
If they didn't expect the landing lights to get hit occasionally they wouldn't make them frangible.
Trikes can ground loop; it's just almost impossible to drag a wing.
Pilots doing IFR approaches don't mind when you make them translate named positions into something meaningful.
Never assume others understand the difference between uncontrolled airspace and a post-apocalyptic world of anarchy where any pattern or approach is okay. Keep your head on a swivel.
Slipping is good for the soul.
Whether or not one is truly lost on a cross country is directly related to how much fuel is in the tank. If you have plenty, you're just exploring alternate routes to your destination.
The sound of one's engine is directly related to the number of emergency field options.
Birds have the right of way.
If you've finally spotted the airport and there are cars driving on it, keep looking.
A tailwind enroute is Mother Nature's way of apologizing for the nasty crosswind awaiting you at your destination.
Corrolary: a headwind is her way of giving fair warning of the same.
Never approach an aircraft without visiting the bathroom first.
Asking passengers not to scream (as it is distracting while flying) during the pre-brief does not instill confidence.
Never trust air pressure in the mains from appearance.
If you didn't touch it you didn't inspect it (okay, that's an old Army thing I was taught).
If crouched, taked three steps backwards at a 45 degree angle towards the front of the aircraft before standing up.
If reported, find out which direction the wind is calming from before selecting a runway.
A loose sectional on the knee board on pre-flight is going to be collected from the floor on post flight.
The carb heat knob has a label spelled C-A-R-B. Pulling the one spelled C-A-B-I-N will fail the RPM drop test every time.
Never write a freq or other information on the inside of the hand that holds the stick.
Never retract a fuel hose while holding it with a bare hand unless there is a bar of Lava soap available.
Never leave a plane unchalked unless you can run three times faster than a four knot gust.
The likelihood of a four knot gust suddenly happening on a "calm" day is directly related to your distance from the aircraft.
Never get irritated by the questions from the old guys hanging around the lobby - think of it as Down Home-land Security. Besides, you can get them to take you around the patch about a third of the time in their plane if you engage them.
If you can't remember if you turned the fuel off or not, you didn't. Go back.
What other gems are out there?