The US military did a study of this back in the day. The #1 contributing factor was... Humidity.

As such, the #1 thing you can do is dehumidify. You won't have too much trouble with rust if you're below around 50% relative humidity.

The trouble generally comes on times with cold nights and warm days. It brings giant swings in humidity and then condensation rears it's ugly head.

Barring that, wipe tools down after each use with a quality corrosion preventing oil product. The easiest place to find them is in the gun section. CLP is a good one. WD-40 is not. Mineral oil doesn't have anything in it that will prevent corrosion.