This text is modified from the original at Rivendell, to customize for my sister and step-mom and any interested new cyclists.
Fun is more important than fast.
Ride only when you feel like it.
Learn right away that the front brake is the most effective one, and don't brake hard in sand or silty road debris.
Learn how far you can lean over without scraping a pedal and learn to keep the inside pedal UP when you corner.
Be the master and commander of your own bicycle. Learn to fix a flat. Never let your chain squeak. That is why you need chain lubricant, $5.
Get a bell. Signal your approach to pedestrians, especially if they're old. A bell is better than "On your left!" but it will do if you're bell-less.
Never hit a pedestrian. In traffic, be visible and predictable.
Don't ride in shoes you can't shop in.
The best bike on earth is the one that you WANT to ride. Feel comfortable mixing high tech and low tech, old and new parts and technologies, and don't apologize to anybody for it. If you buy a new bike, do something to it that makes it the only one exactly like it in the world.
Compliment other people's bikes, especially if they're old and well cared for.
Buy the cheapest helmet that fits well.
Don't always shop by price and never ask for discounts at your local bike shop. Every time you go into a bike shop, spend at least $2, and if you ask a question and get good advice, spend $5 (get a cable).
Never apologize for buying something that's not quite pro quality by saying, "I'm not going to race or anything."
Have at least one bike you feel comfortable riding in a downpour. Ride in weather that keeps other cyclists indoors. ENJOY being outside, even if it's wet/humid/cold/hot/dark...
If you borrow somebody else's bike, for a short test or a long ride, say something nice about it.
Photo and Rivendell tip inspiration taken from Sydney Body Art Ride blog. Thank you!