The salient items are:

• stop at all stop signs and red stop lights unless otherwise directed
• call out sudden changes in speed or direction: slowing, stopping, rolling, turning
• announce that you are passing, and do so only where it is safe and always to the left; always look to the back to ensure you are not passing right into a moving vehicle
• always ride where it is safest - as far to the right as possible on the shoulder, at least a car door width away from cars to your right, never ever into freeway lanes
• ride single file
• always wear a helmet when you are straddling your bike
• never wear anything that prevents you from hearing (MP3 player, phone, bluetooth headsets)
• always keep both hands on the handle bars; remove one hand only when it's safe
• always keep at least a bicycle length between yourself and the next rider, and try not to ride directly behind their rear wheel

There are trillions of zillions of other rules: never eat anything on the bike, don't ever draft anyone, never pass more than one bike, etc. They are frequently ignored and can cause risk, but the ones I listed above caused accidents in my real life experience on the ride.