Brass does not like to stay wet too long. When you want to give it a wash use mild soap and warm water and make sure to dry thoroughly.
If you like your brass shiny then you will have to regularly polish it, a natural way is to use a mixtures of lemon mixed with bicarbonate of soda and rub it on the object. Or let the brass tarnish naturally.
Marble is quite a strong material. Washing with a mild soap and warm water is the best way to clean it. However it does stain. The best way to try to remove a stain without using heavy duty chemicals is to spray the stain with water, then create a paste by mixing bicarbonate of soda and water, apply the paste to the moist stain, wrap it in cling film for 24 hours and let it sit. Once the time has passed clean the stain normally. If not too deep the stain will be removed.
Never saturate wood in water, as it may bend. Dampen a cloth with soap and water and scrub away but make sure to always dry the wood once you are done cleaning. Another way to keep your wood happy is to oil it every once in a while. You can oil it by rubbing it entirely and evenly with almond oil. Wood loves a good massage.
Glass can be put into a dishwasher or be cleaned by hand using dishwashing detergent and lukewarm water.