Nubuck leather is known to be a very delicate leather. It is an aniline leather, which means it's the most natural type of leather available, which also makes it the most expensive. Like suede, it has a raised-nap finish which was created by lightly abrading the the grain surface. Despite being delicate, however, cleaning nubuck leather is a fairly simple process.
The first thing you need to do is brush the leather with a cleaning brush. If there are any stains on the piece, you can use a nubuck stain eraser. If they are grease stains, use a de-greaser specially designed for nubuck. After attending to the stains, spray a cleanser onto the leather and rub this with a cloth, working in sections, and not staying in one section too long. If you feel an area is still dirty, return to it later. Constantly moving the sections will help you keep the leather looking even.
An alternative to the spray cleanser is to use some nubuck cleaning paper and wrapping it around a bottle. Then, begin rolling the bottle over the piece. The nubuck will clean the paper, while the bottle helps keep the cleaning motion smooth and even. Keep rubbing till you begin to notice that the leather is getting cleaner.
After cleaning, brush the leather with a napping brush. This will help separate the fibers and bring back its natural fluff, restoring the original appearance. Remember to work in circles, not brushing too long in one place. If you don't have a napping brush, you can also use a soft sponge, rubbing the nubuck the way you would clean a kitchen counter.
The last step is to spray some Waterstop or other protective formula. Let the first spray of Waterstop dry then spray on another layer. This will protect it from water and oil. Since this commercial protector will have to be applied every six months, cleaning your nubuck leather every six months is a good schedule.(If the nubuck is exposed to water, blot it dry with a paper towel then let it air dry completely before applying some more protective spray.)
In between six month cleanings, vacuum it gently every couple of days. Once a month, you can run a piece of very fine sandpaper over the surface of the nubuck. If you do this, the six month schedule for cleaning nubuck leather will be much easier, and it might not even need to be as often.