When riding with passengers, remember to ride safely and obey all laws including the speed limit (as you should every time you ride). You now have the responsibility of transporting, not only yourself, but also another person. You should never take any chances or risks while with a passenger.
Inform your passenger of how to ride with you on the snowmobile. Tell him/her to keep their feet flat on the running boards, firmly hold the handgrips, and to lean into the turns with you.