Don't worry about the orientation of a dipole when it's less than a half wavelength above ground.
In multi-multi contesting and big gun DXing it's often more a battle of bank accounts than operator skill.
You're going to go through several phases in your radio artisan career. Don't spend too much money until you're sure you like the phase you're in.
Don't gauge your success by the number of awards you have on the wall.
Don't get your start on 2 meter repeaters.
Don't be nervous.
Your money is better spent in antennas than amplifiers.
There are good CBers and bad CBers. More amateurs than you think got started on CB.
There are jackasses in amateur radio. You cannot identify them by license class, age, years licensed, call area, operating mode, education, or income.
When the bands are open any goofy antenna will make contacts. People will think this makes a goofy little antenna a good antenna. Not so.
The perception of amateur radio that the general public holds is much different from the perception within amateur radio. We're in a strange, esoteric and sometimes archaic hobby that most of the world doesn't understand. Welcome to our secret society.
It's not that extra one or two dB that makes the difference, it's the first 50 dB that really matters.
Girls actually dig letters written in Morse code while you're dating.
Save your money and buy a crank up or tilt-down tower.
You can operate anywhere you live, no matter what the restrictions. About any piece of metal can be loaded up with a tuner.
You buy an HF quad only once.
Low SWR doesn't mean it's a good antenna.
Homebrew it, even if you're not some master electronics designer. When building equipment, don't worry about not being a EE or building the perfect circuit. Don't bother making printed circuit boards, you can build just about anything you want Manhattan style. Experiment. You will learn more from your building failures than your successes.
Don't fall in love with one brand of radio.
Don't limit yourself to one mode.
Join a club. Do what is fun and what you want to do in the club. As soon as others tell you what you should be doing, it's time to leave. When being involved in a club feels more like a chore, get out. If the club is on life support and you can't revive it in three years, pull the plug. Move on. Don't look back.
QRP isn't difficult. It requires persistence and patience....and knowing when to go QRO or when to QSY.
If you are in a club you don't like and you want to leave that club to create a new or rival club, list on a piece of paper why you don't like that club. This list is why you shouldn't start a new club.
Don't do CW because you want to impress others.
Get a ARRL life membership as soon as you can afford it. Don't worry, you will get angry at ARRL at some point, but you'll save money on the magazine subscription. And ARRL is about the only reason amateur radio is still around.
It's never what you don't know that bites you, it's what you don't know you don't know that gets you into trouble.
Walk away when you need to.
In amateur radio do what you like, like what you do.
You're in a great hobby for life.