Depending on the condition of the piece and the look your after will determine what is required, sometimes all that is required is to simply wipe with a damp cloth and other times require polish or waxing.
Never use commercial silicon based sprays as they leave a residue behind. The best way is to make your own polish, simply put a little turpentine with boiled linseed oil in a spray bottle and shake to mix. Spray and wipe small areas at a time with a clean cloth. The more you rub the better it shines. This will bring up the color and grain of the timber, it also helps to hide imperfections such as small chips and scratches