Sorry for the lengthy list , but here are a few more I just thought of....

If you take a newbie fishing, he/she will catch the biggest (and sometimes only) fish of the day.
Never wash your fishing vest.
Flycasting into the wind = wind knots.
If you accidentally hook yourself, do not let others see it (and never admit to it).
Report environmental damage. If you don't, who will?
If you get sand in your reel, DO NOT try to turn the reel handle.
Try surf fishing at dawn at least once. You will surely want to do it again.
You will never forget your first trout.
Always treasure catching a wild trout, and release it gently and carefully.
Not all streams flow North to South (as on a map). Do not use it as a compass.
If the trout are only hitting size 24's or smaller, go bass fishing.
Do not use your teeth to pinch split shot onto your line. It's LEAD!
Leave bad attitudes at home....