When I didn't dive year round, there were a few tricks I had for storing.
Put regs, computers and cameras in a drawer where summer clothes are stored, i.e. inside is best. I would hang my BC and wetsuit (on a very thing hanger) in a storage closet. Tanks, fins, and other accessories stored in a dry place without large temperature swings. Plus what everyone else said.
For those diving year round: it's that time of year that if you were charging re-chargable batteries (lights, cameras, DPVs) in the garage, bring 'em in. Often rechargeables, esp. NiMh cells, don't like being charged in anything other than "comfortable room temp". (And no, not Matt S's comfortable room temp.) Storing them indoors is also not a bad idea.