Dress for the crash, not for the ride. Buy and wear the best protective gear you can afford.
Stunting is for empty parking lots, racing is for racetracks. There is no trophy at the end of a street ride.
Learn to use and trust your front brakes.
Even the best tires have limits. Acceleration, braking, lean angle can each be impressive but too much of either combined can lead to disaster. Learn the limits.
Be smooth. Roll on the gas, gradually squeeze the brakes, learn proper body position movement and learn to counter steer. Smooth doesn't mean slow. Smooth is key to being fast and always in complete control.
Always look where you want to go. Target fixation, especially in panic will take you right where you don't want to go.
Properly maintain your ride to avoid issues, and always fill up before heading out. You don't want to be "that guy" that runs out of gas and ruins the fun for the group.
Ride within your limits. Just because the guy in front of you made it through that turn doesn't mean you will.
And good gravy, put your kickstand up before taking off! Oh, and get on and off from the kickstand side so you don't look like a rookie dweeb, even if you are one.