Lock your gun in a cabinet, preferably hidden within a larger storage area. This will prevent curious children, house guests or even burglars from accidentally mishandling your gun.
Keep all cartridges and other ammunition in a secured cupboard or out of reach of children. Firearms ammunition must be locked in a separate container to the gun.
Even if you know it is unloaded, it will scare somebody if you point any gun at them. Are you absolutely sure that the gun is not loaded?
Don't leave bits of oily rag in the bores of the gun with the intent of preventing rust. If the gun is properly cleaned and stored, this will not help and you could so easily forget the rag is there.
Treat a gun's safety mechanism only as a second line of defence because it could be faulty. No one was ever shot by an open, empty gun.
Guns should be locked in the boot or placed in the back of an estate car under a cover (e.g. travel rugs and coats).
Keep your gun in its container until you are ready to use it. Carry the gun to the location in its slip so that if it rains, there is somewhere dry to stow it. Open the gun as you take it out of the container - that way it can immediately be seen to be unloaded and that the barrel(s) are clear. Keep the gun broken until just before you are ready to fire it.