So, you scored a seat on the snowcat. Now for a lesson in how to do it right.
1) Pack heavy
There's no need to go light today. Bring all of your favorite layers/jackets. If one gets wet, change it in the cab. You'll spend your day 50/50, half in the 'cat and half on the snow, maybe 15 to 30 minutes each. In fact, ditch everything you don't want to carry in the cab. That goes for gloves and beanies too. Have set of dry everything.
2) Avy savvy
What? You have all of your own avalanche safety and companion rescue gear? Great. Turn your transceiver on to send. Now, ditch the rest in the cab and grab the pack shovels most 'cat companies will have ready. Guides are there for rescue, you are there to dig. But don't worry, at the slightest hint of an avalanche issue, guides will head for low angle tree runs far removed from avalanche terrain. Tree wells, now that's another story.
3) Powder vision
If it's a good day, goggles are working overtime. You might note goggles come off immediately in the cab to air out, hung from loops hanging from the ceiling for this exact purpose. Even better, bring a goggle with interchangeable lenses, and bring a few extras lenses. Dry one on your next run.
4) Hydration variation
Many 'cats will have a giant jug of water but it may be outside the cab. Having a go-to water bottle is a great way to fill up in between runs and not have to carry that heavy water weight on your skis.
Guides may seem like superheroes, and many are, but turns out ski guiding isn't a get-rich-quick scheme. Pro deals and powder don't pay the bills, these folks depend on tips and tipping is a part of the process, like someone who waxes your skis or shoveling your driveway. If you a) had a good time and b) lived to tell about it, you should tip accordingly. Ten to 20 percent should do.