Trail etiquette

1. If you are riding downhill and meet someone riding uphill; the person working harder riding uphill has right of way, you should yield to them. Yield means make sure they have room to ride past you, if that means you have to stop, then stop.
2. When riding in a group, all you have to do is make sure the person behind you takes the right turn at trail junctions. If someone gets lost it's the fault of the person that was in front of them. Riding like this allows you to go longer periods without needing to regroup and really keeps the flow going. 
3. When stopped, make sure the trail is clear so people can ride through. Be especially careful that you are not blocking or confusing the area around any sweet jumps. 
4. Ride it don't slide it. no skids! 
5. Don't ride when it's muddy. I usually wait 12 hours. If it hasn't rained in a while the trails can soak up 2 inches of rain in almost no time. If the ground is already pretty wet it can take a long time to dry out. 
6. Trail maintenance doesn't have to be a whole Saturday on a crew. you can clean deadfall, dig a drain to clear a puddle during your regular rides. 
7. Pick up trash, especially bike related trash. 
8. Say hello to everyone! 

any more to add?