I had posted this years ago on another site and in deference to them I will post the link here as well as the text. These rules are not limited to flyfishing, so don't be too offended.
Rules of Fishing (Guest Article)
by Scott Lux
Muddy water is deeper than your waders.
Clear water is probably deeper than your waders.
Fish almost never reward a perfect cast.
More equipment doesn't mean more fish.
More expensive equipment doesn't mean bigger fish.
Don't stand in a canoe to set the hook.
The colder the water, the more likely you are to fall in it.
Never take bait home with you. You probably won't use it and the fish will be more likely to take it next time if they get it without a hook this time.
People can see you from the road (house, barn, etc.).
No Trespassing means NO TRESPASSING, even for you.
Your wife (girlfriend, child, etc.) will catch more than you do.
Four-wheel drive lets you get stuck farther away from help.
If you don't want to spin in the wind, anchor at both ends.
Always carry a spare bilge plug.
A spare propeller and pin is not a bad idea either.
You'd be amazed how many fish there are less than one hour from your home.
A bad day fishing is better than a good day working.
Water leaking in waders is always just above freezing.
Big fish wait to splash until you're leaving.
Leave the river (lake, pond, etc.) cleaner than you found it.
A fish mounted on the wall is of finite size.
A released fish can be exaggerated as needed.
Lures are designed to catch your money.
People who are serious about fishing rarely drink beer while doing so.
Big fish will hit small lures. But, so will small fish.
It is possible to land a 5 pound fish on a 2 foot Snoopy rod. Ask any kid.
The perfect boat is one that someone else maintains.
Fishing is a privilege, not a right. Treat it as if you could lose it.