Marble is one the most beautiful albeit porous stones. Seal it with a stone sealer when it is new because it is very susceptible to stains, and wipe up spills quickly because marble absorbs moisture. It also can be easily scratched by grit. Be realistic about your expectations when you have real marble flooring or furniture. It probably will not maintain its showroom shine and some scratching cannot be avoided.
Clean Marble regularly by vacuuming or sweeping it first and then using a soft cloth or sponge with a solution of mild liquid soap and warm water to wash it. Do not overwet the marble, instead use a damp cloth or sponge and keep the cloth or sponge clean as you work. It’s a good idea to rinse marble and dry it with a soft cloth after washing. Do not use acidic products, such as vinegar or lemon juice, as they will etch the marble. As you are washing, if you find spots that are not responding to the washing solution, sprinkle on a little Borax or baking powder and rub with the damp cloth or sponge or use a commercial marble polish available at hardware stores or home center stores.
When you are spotting marble remember that warming it first with a blow dryer will open the pores and make it easier to remove the stain.
To restore the shine to marble, rub with a cloth dampened with turpentine and then buff well. Dispose of the cloths outside in the trash when you are done.
Maintaining the beauty of Marble is an ongoing but rewarding venture. It will last a lifetime.