So now you gallop off down the trail, right? Not such a good idea. You are still in the parking lot area, with lots of people, other horses, etc. If your group goes charging off, the other horses may spook or kids may dart in front of you and get run over. It's always better to walk your horse the first 15-20 minutes to warm them up anyway. So mosey quietly out of the staging area and out on the trails.
While on the trails, remember the Trail Etiquette guide. Be polite to other trail users, but also be prepared for them to not understand horses. Don't hesitate to call out if someone has a loose or barking dog, but be sure to thank them after they have caught Cujo and restrained him. Let safety determine your speed, and always remember to ask the group if they are ready before a change in speed. Nothing more alarming than taking your feet out of the stirrups to stretch just as the person in front of you decides to work on racing departs. Call out to the riders behind you if you spot any trail hazards, such as low branches, holes, glass, etc. If you are leading the ride, remember the pace (and difficulty) of the ride is determined by the lowest level horse and/or rider. If you have a 'white knuckle' rider, you aren't going to be galloping the trails that day leaping every tree and deadfall you find. If you have a green horse along, probably not the day to explore the cliffs and slides along the river. Keep track of your group, and make sure no one is left too far behind. When you get to an obstacle, such as a log or water crossing, stop, give everyone a chance to catch up, then slowly cross. After you have crossed, move on so the next horse has room, but do it at a slow walk so the following horses don't suddenly think they are being left behind. Always wait until the last horse is clear of an obstacle before speeding up the gait. Any horse can feel abandoned on a ride, and rush to catch up. That's when horses slip, get caught, etc. and riders come off. A little common courtesy prevents a lot of possible problems.
Remember, the goal is for everyone to have a fun and safe time.
Now get out there and ride!