PREPARE YOUR HORSE FOR THE TRAIL
Good trail etiquette is possible only if your horse is prepared for the trail and what you might encounter there. If he is terrified of motorized vehicles, stick to trails that exclude them until you safely desensitize him to the sights and sounds associated with dirt bikes and the like. If he is OK with hikers in general but sees walking sticks, backpacks and children as menacing, then he’s not ready for public trails---and you need to work out these issues at home beforehand.
Of course, you can’t anticipate every challenge. There are times when my normally sensible horse gets spooked by a group of rambunctious kids running on the trail or a bicyclist who suddenly appears on the horizon moving like a mountain lion. Even then, as I’m taking up the reins and hunkering down in the saddle, I try to remember that kids have a right to run and cyclists have a right to go at reasonable speeds. I can’t control what anyone else is doing on the trail, but I can control, to the extent that any equestrian can, my horse.