If you maintain a positive attitude, it will be easier for your horse to focus.
Be committed towards success and be willing to work within your horse’s capacity to learn new skills regularly. Educating a great trail horse takes time, as much time as is necessary, which doesn’t mean 30-day increments. It may take years to develop the ultimate companion horse but it is well worth it.
Start with a single horse and rider and if all goes well, then move on to a group of two or three riding partners before joining a larger group. Introduce a new element of possibilities one at a time. Horses love security whether it is a familiar horse trail riding, or being in familiar company. If any of the elements change, be prepared for new or slightly different behavior from your horse.
Tip the herd dynamics scale
If you find that your horse has more problems with herd dynamics than you anticipated there are a few things that I have found useful. Get your horse comfortable working with other horses by trotting two or three around the round pen as described in Liberty Training II (issue).
Work a dominant horse in the round pen while mounted on a more timid horse. Go easy as the goal is to slowly herd the more dominant horse. Keep enough distance between horses to avoid being kicked and always carry a long whip for this exercise.
Tie horses that will be riding together in close proximity several times during the week for varying periods of time before riding them together.
The Human Equation
Choose riding partners carefully. Consider each horse/rider combination as a team. Choose the best team members you feel comfortable with, that you like and that you trust. In preparation for large equestrian trail riding, introduce trustworthy riding partners to your horse one at a time.
Planning helps to prevent long term problems, so get pertinent ride information before you commit to any group ride. Here are some examples: How many horses will be included? What is the level of difficulty for the trails that will be ridden? Are there ride rules or guidelines to help provide a safe atmosphere? Is there a ride steward or trail boss?

Be a defensive rider. Don’t assume that all riders or horses are courteous and well behaved. The nicest horse on the planet is capable of some surprising behavior when put in a new or stressful situation.
Be aware of your surroundings and of group dynamics at all times. Be constantly conscious of the change.
Pair up with an experienced horse and rider until your own horse is comfortable. If we take out more than one green (inexperienced) horse in a small equestrian group, we pair each green horse with a reliable horse.
Choose a human/horse teammate that will allow you to buddy up with if your horse needs a calming influence or even help in negotiating an obstacle.
If you have any doubt at all that you can control your horse in any situation that may arise, it means that you are probably not ready to join a group ride.
A great source of information for trail riders is “Trail Riding” by Rhonda Hart Poe. Study up on trail etiquette and observe it.
The goal of preparation is to help a horse develop the skills required to be a solid and steady mount in any situation. In other words, the Ultimate Companion Horse.