Take advice from a repairer you trust in the same climate as yourself. Seem to remember one in Vacaville years ago. I'm a UK based, retired repairer.
People have on occasion brought cameras to me that they've tried to "repair" with WD40. And RUINED them! Great for motorcycles, OK for locks but death to cameras.
Cameras like a reasonably constant temperature; if you see condensation on your lens it will also be on internal metal parts. Sweat from your hands on those really hot, humid days - rain, obviously, avoid.
For storage keep in a cupboard or cabinet away from direct sunlight - not too much of a problem here in the UK - away from heating radiators or appliances, preferably against an internal wall, not in a kitchen or bathroom. If you have a spare room, great. We breathe out moisture all the time so if your cupboard has to be in a bedroom or living area choose the bigger room if you can to minimise humidity.
"Airing cupboards" are found in some houses in the UK - the hot water tank is in there - great for drying towels but will dry out some lubricants in cameras and cause others to separate & migrate. Leather can crack, adhesives can fail.
Exercise is good if you have the discipline for it, most of us don't. But if you can manage it, using them regularly helps to keep them moving.
Having said all that... I have some cameras that have been untouched in boxes for up to 25 years. Just now put batteries in four of them and all work fine!
Some will disagree but I don't use desiccants or plastic bags - each item I wrap in a square of undyed clean cotton cloth. Mostly because I've never known for certain all the possible causes of degradation of light-trap foams.
Hope this is of some help but don't forget I'm at least ten years behind the times...