Recommend a good desiccant.
Here's what I do. I go to the pharmacy and ask them to save the desiccant cannisters that come in their larger jars of drugs. They transfer the drugs to smaller bottles as they dispense prescriptions and then throw away the silica gel. After a week, they've saved enough of them to fill coffee can for me.
I prefer the solid cannisters with silica over the little bags. I don't want to introduce dust into my camera bag.
I'm a woodworker and thus have several hundred high grade steel cutting tools. So I pop silica capsules into every drawer of every toolbox. Then, every few months, I gather them up, toast them in a 150° oven for an hour to expel moisture and recharge the silica. The plastic on the capsules will melt, so keep the temperature low enough to avoid that, but high enough to drive out the moisture.