One of my 'it makes things easier' is to use magnets for holding things. Specifically, say I've got a pistol I've wiped down with Eezox and I don't want it laying on a cloth or something while it dries. I've got a file cabinet next to the table where I do things like that, so I put the piece muzzle-down on the table and set a magnet on the cabinet where the butt touchesand it'll stay there while the stuff dries. Or penetrating oil soaks in or whatever. You can do this with a rifle or shotgun(minus the stock), though I'll generally use two magnets, one on each side of the receiver or barrel, for that to make it more stable.
I'll throw in, you know those plastic clamps you can pick up at Harbor Freight or wherever on sale? Nice & strong? You can clamp two of them on the table and lean a long gun between them so it can't fall over.
Probably these are methods you're aware of, but just in case.