You will be sharing the trail with other users no matter where you ride. They may be other snowmobilers, grooming equipment, other recreational users, road users if the trail is on a road, and, most definitely, wildlife. Most, if not all, will have just as much right to the trail as you do. How you approach their presence makes a great deal of difference in how safe the trail is for everyone.
Stay to the Right
Yield to other traffic when necessary.
Be aware of faster riders overtaking you from behind. Let them pass.
Never block an intersection.
Never stop side-by-side on a trail.
stop in the middle of a trail.
Yield to trail groomers.
When encountering automobiles and trucks on shared-use roads, stay to the right, go slow, use the kneeling or standing position to be more easily seen, and always yield to the vehicle.
Be polite to other trail users: remember that you are an ambassador for your sport.
When you encounter skiers or snow walkers, slow down to the minimum to maintain forward motion. When you encounter dogsleds or horseback riders, slow to a crawl, and yield the way.
If you encounter ATVs or motorcycles, remember that they do not have the control and maneuverability of a snowmobile, and must be given lots of room.
If you are lucky enough to encounter wildlife on the trail, slow way down or stop entirely so as not to alarm the animals. You'll get a better look that way. Never chase or harass wildlife.
No matter who you meet on the trail, ride sharefully. It protects your right to ride.