Don't care much for "old fashioned" single action pistols or revolvers except for fun. I do have a little Beretta .25 Jetfire. With saftey on, tilt up the barrel (nice feature only on Beretta blowbacks) remove the round, drop the mag, turn the safety off, put your thumb on the hammer, depress the trigger, and in a slow controlled manner let the hammer down (care not to stop at half cock, or you will repeat the whole thing). Easy on a little gun, a bit trickier on a larger one. Practice.
Use the same extreme care in dropping the hammer on a loaded (god forbid) DA revolver (modern hammers do help to avoid accidents - but how else do you do it if you are stupid enough to cock it and not fire it) that you would with any SA pistol. Can't imagine dry firing to lower the hammer unless the gun's design does not allow any other way ?
Did I mention modern de-cockers scare the crap out of me. Anyone else? Just doesn't seem safe.