Backing off valves

I live where the temperature changes lead to a lot of condensation. Outside, inside, everywhere unless the storage is temperature controlled. I.E. it's 60+ degrees this morning. It was 24 on monday, and will be 30 tomorrow morning. That's normal for CT so fogging is a big deal and firing it and letting it idle a few times a month does nothing but put water into the exh system. If you can't drive it, leave it alone. If you have a decent cam it can't hurt to let the valves close. It could hurt to leave some of them open both in terms of an open cylinder (condensation or critters) and valve spring tension (reduced service life for those few that are stored at partial or full lift).
Your prep should be particular to the vehicle, your geographic location, and the length of storage.

Yes - drier sheets! The stinkiest ones you can find.. They get put in my tractors, my cars, my girfriends car, and my truck. They work better than moth balls and don't need an explanation in the spring as to the smell...lol.