Rights of way
In England and Wales, cyclists have a right to ride on bridleways, byways (including restricted ones), unsurfaced roads, canal paths, routes with other public access (e.g. 'white roads' or 'green lanes'), Forestry Commission stone tracks and some unsurfaced Forestry Commission tracks. However, the law states that when riding on bridleways cyclists are required to give way to pedestrians and horse riders.
Other trail users
On public rights of way you will encounter walkers, runners, horse riders and other cyclists. A bell or polite greeting is a good way to indicate your presence and not startle them. Do this early and be prepared to stop, as is the law. If approaching head on, slow down, keep to the left hand side of the trail/track and make your intentions clear. Often people will beckon you through, if so, pass slowly and thank them.
On event day there will be large numbers of riders, which as well as being inconvenient for other trail users, can be intimidating so pass slowly and be polite.
If you encounter a slower rider be considerate. Do not ride aggressively or get too close, this will unnerve them and can cause an accident. Let them know you are approaching and be patient. When there is a suitable place to pass, let them know which side you intend to overtake (e.g. "passing on your right"), wait for them to hold their line and thank them as you pass.
If you are the slower rider, allow the rider behind to pass when you feel it's safe. Don’t panic, continue to ride as you would. If the trail is wide and safe enough, move to one side, indicating you are doing so. Listen for any instructions from behind.
Don’t obstruct the trail
If you need to stop for any reason, try to do so off the trail, or where you can be passed safely and easily. Stopping suddenly will put yourself and others at risk.
Ride to your ability
Choose routes/events appropriate to your skill and fitness level as well as being suited to your bike. This will reduce your chance of having an accident, and also mean you are more likely to achieve your target and enjoy the experience.
Don't skid - it shows poor cycling technique and damages the trail.
Don't go around puddles as this worsens the problem. A puddle will normally indicate a hard surface underneath - whereas it will be muddy around the edges.
Always shut and fasten any gates you pass through - even if it was already open, as this probably means someone else has left it open. If in doubt, close it.