Let me be more detailed, First, I always keep a UV or 1A filter on just to protect the front elements. My choice is B+W or Helopan due to optical qualities and my being a snob. It's impossible to keep all the smutz off the lenses so I carry two small trim (chip) paint brushes to clean off the "stuff". One 2.5cm with the bristles cut short and one 5cm. The focusing helical and f stop rings need some protection and a wide rubber band can really be helpful but unless dunked, they are well designed and can be brushed out.
if you feel grit when you focus, stop and use a (chip) brush to clean out the grit before it works itself into the helical. When you change lenses, point the lens down to avoid moisture getting into the mirror box.
In extreme cold, leave the camera outside your clothing to avoid moisture condensing and causing that series of problems. Again a plastic bag open on the botton to allow airflow can do wonders. When traveling in the Negev dust was the problem, not sand, in Asia it was humidity (!) and in Europe rain rain and more rain so I often use an EWA bag to protect the camera if I really had to shoot, but usually just a heavy plastic bag. It may look dumb, but a 3p glad zip-lock bag can save you big bucks in repair. Be sure the bag is really clean inside and don't leave the camera in the hot (direct) sun inside the bag, for that some aluminum foil can be a real help. I also have a silica gel canister in my bag to try keep things dry. I think I got it at Porter's many years ago, be sure it's the type that can be heated to recharge it
If you can keep the majority of "elements" off the cameras you stand a better chance of aclamating them without damage. You have to understand that in extreme conditions the equipment might not work the same so don't force anything! A lot of common sense can save you a ton on money. I hope this helps