1. If you are storing small amounts of water it will freeze overnight. Ask me how I know... Try to insulate it somehow so you have liquid water to drink when you wake. Or leave it in the car not the tent.
2. If you do decide to do dishes bring extra propane, heat some water on the stove and use hot/warm water to do dishes. Freezing hands is no fun when it's cold out. Avoid dishes if possible with pouch foods or paper plates, etc.
3. Sleep with a beanie on. Military style fleece beanies are awesome and cheap.
4. A real, properly temperature rated sleeping bag is great, otherwise layer sleeping gear.
5. Have fresh socks & your clothes already in your tent. Wake up, change if required, go. Sucks needing stuff when you wake up in the cold and then you have to climb out of that tent to get it and then go back up. PITA.
7. Hot coffee first thing if you're a coffee drinker. Hot coco or tea perhaps, if your'e not. Sets the day in the right direction. :)
I don't yet own a Tepui WeatherHood but I think that's going to happen after this trip I just finished. I think it really would have been great for some of the sub-freezing nights and definitely for any future snow camping.
Enjoy.