There are a few things that you’ll need to get to make sure you are ready to snowmobile. The snowmobile rentals come with jacket, pants, helmet and boots, but you do need some other stuff
You have to have good gloves. It gets cold up on the mountain, even though the valley isn’t always that cold. Finger gloves are required - they will not let you on a sled with mittens.
Jon has actual snowmobiling gloves - the Castle X Epic-G1. You don’t have to get snowmobiling-specific, but I find them to be a little more comfortable for dexterity and stuff.
You want one thats hinged, ideally, so you can pull it down over your chin or back up to cover your face. Both MJ and Jon tend to go back and forth on if their mouth is covered as its a really good way to regulate body heat while you are riding. You definitely don’t need to go all out for this though.
I don’t care what anyone tells you - GET WOOL. This is basically all I wear under the pants and jacket, and its so nice to be cozy. Jon wears a combo of Smartwool, Meriwool and Icebreaker. MJ got Patagonia ones from REI last year that she really liked.
Same as above. Get warm ones. The boots are definitely warm, but especially standing around in the snow - which you’ll definitely do - it can get chilly.
You need goggles. For you glasses wearing folks, MJ got some on Amazon a few years ago that work good for her on both snowmobiles and snowboarding. Jon wears a pair of 509 Ssnowmobiling goggles. If you can get ones that have replacable lenses, I kind of recommend getting two - a darker tint, and one that is better for contrast (like a yellow or rose). The color makes such a difference, I find, and having a second lens is nice if you fog up