Beretta uses an anti-corrosive rust protective on its guns. Clean it off the moving parts, exterior surfaces and inside of the barrel.
Lube the rails, magazine tube (outside), bolt, breach block with oil, Break-Free or other like lubricant. The Berettas like to be shot "wet." The gun doesn't need to be dripping but don't be shy about the oil.
Here's a hint on reassembling the gun. Take the trigger assembly out and reinstall it last. It makes it easier to align the internal parts without the trigger assembly in place.