Most old furniture would have originally been waxed or French polish. To care properly for your antiques avoid silicon based products. Natural beeswax polish is good to use. Natural beeswax comes as a spray or a thicker paste from a tin. The thicker paste can be applied using a soft cloth or a stiff brush, especially on carving. Both can be buffed up with a soft rag, old towelling is perfect.
You can make beeswax paste easily, using a 1lb of yellow beeswax and half pint of good quality white spirit. Wrap some yellow wax in towelling and break it up with a hammer or mallet. Put the broken beeswax into a tin, add the white spirit, put a lid on, and leave overnight. Within a day or two, and some intermittent stirring, you will have a thick paste, ready for use.
Here are a couple of recipes to revive waxed or French polish surfaces on antique furniture
One part raw linseed oil
One part methylated spirits
One part white vinegar
Twelve parts white vinegar
One part terebene driers (unleaded petrol will do the same job)
Four parts raw linseed oil
You can use a soft cloth with warm soapy water to wash the worst of the grime off first. Once dry, the reviver can be used. Apply with a cheese or dish cloth, in a circular motion to start with, but end up working with the grain. After, apply your beeswax, and bring back the shine and patina
Try to avoid putting your furniture in direct sunlight as this will cause wood to fade. If furniture is put in front of a window, it is worth closing the curtain or blind during the worst part of the day.
Watermarks and wine rings can be removed by a professional polisher. Most antique restorers generally believe that minimal alterations are best, though cleaning is acceptable.
It is also worth noting that light woods darken, and dark timbers lighten, so your honey coloured walnut dining table would have started life nearly black, while your dark Tudor four poster bed would have originally been golden in colour.