After each session:
For stainless steel, copper and titanium, all you need is a cloth, water and a maintenance product from time to time to restore the shine.
For the sweet-iron, you rinse your bit well with water and dry it with a towel (no need to take out the hair dryer…)
For leather bits, a wipe down after mounting and an oil bath (kerosene or olive oil) about once a month.