Fingers inside, resting against the outer part of the loop rather than against the stock. That way, I don't smack my knuckles as hard when I cycle the action.
I hunt with an empty chamber. When I'm ready to shoot, I run the lever as I'm raising the rifle to my shoulder.
If I'm practicing, then I cycle the action after each shot with the rifle still at my shoulder, as rcmodel posted above.
Once I've taken a shot at a live animal in the field, I wait, rifle shouldered and watching, before I run the lever again. I leave the hammer down on the fired case and watch to see whether I'll need to move before firing again. An adrenaline rush / buck fever / tunnel vision makes it possible to go running across a field with a cocked hammer over a live cartridge. No, I haven't done that. Don't want to.
If I need to shoot again, it's quick and easy to run the lever without dropping the rifle from the shoulder.