Never hand it over loaded. There's no rush unless you are engaged in mortal combat. Open the cylinder, drop the ammo out into your hand, hand the revolver over with the cylinder out and your fingers through the frame so the cylinder can't close.
On a singel action, unload the gun, open the loading gate, spin the cylinder to make sure it's empty, then show him it's empty by spinning the cylinder so he can see that it's empty.
Semi autos: drop the magazine out, open the action. make sure there is nothing in the chamber. Lock the slide back. Hand it over so he can see it's empty.
Never accept a gun from someone any other way.