stock on my 39A. First clean the stock with a rag with alcohol set it aside and let dry for 24 hours. I then use 400 grit sandpaper and sand it by hand to remove the existing finish and little dings and scratches. I then finish with 1500 grit sandpaper to get as smooth a surface as I can. I am working on the butt stock now as I have already finished sanding the fore end. After that I intend to use a quality Valspar stain and then use a Satin Finish to bring out the grain in the wood and protect it. This is just my way of doing it and others will have other advice I am sure.
If you intend to clean metal and the wood then remove the stock before putting any solvents etc on the metal. Oil and solvents tend to migrate to the wood metal interface and can cause the wood to deteriorate and cause dark bands in the wood that can go up to an inch or more under the surface of the wood.
This is just my way of doing things and as I said before others will have their own way of doing a clean job on a fine old gun!