For reg cleaning, I use soap and water (Dawn is real good) to brighten up brass when it get oxidized to the point I get low performance/ warm switch, I use a very soft and non abrasive cleaner by Weimans. Its supposed to be good for food items, so I can use it on my DT.
For stainless steel I just use soap and water and acetone on threads and high percentage alcohol where there might be contact with orings.
If my Stainless gets real dirty or I use one of those sunshine cloths but if it has engravings you have to be careful because even the sunshine cloths have micro abrasives and will eventually smooth out light engravings/logos.
For used items I get that are dull and have lots of surface scuffs, I wash in hot water, scrub threads, then I take some autosol which is lightly abrasive, rub it trying to follow the brushed finish as not to mess it up.
I know that many used autosol on mirror finished items but Ive always been a bit hesitant. I have that old GUS that is mirror finished, it has lots of surface micro scuffs, but am nervous about making swirl marks or any rub marks on it. I do use a sunshine cloth on it and figure, I can live with the "character"
Getting rid of surface scuffs on brushed devices I just finish the autosol rubbing, with a scotchbrite pad wrapping it around and turning as evenly as I can to mask the scuffs.