I have restored both uprights and grands in the past along with organs and harpsichords. Your pictures do not tell me enough but this appears to be an upright from around 1920. It is not worth putting a lot of money in it for resale but if you are keeping it, it is probably superior in sound and touch to most of the "spinets" (excepting some of the big namds) now on the market, if it is reasonably intact and properly restored. I would certainly move forward on your project if you are keeping it. Most of these instruments were sprayed with a shellac/stain mixture in a factory and this finish becomes opaque through the years. What lies underneath is often far more attractive than found on a modern piano. Usually it is a mahogany veneer, thicker than the modern stuff- sometimes as much as 1/16. The standard finish that most shops apply to this type of piano is-
1) Strip the old finish (as Steve indicated) with alcohol (shellac thinner) and steel wool. Woods chips also help a lot to sop op the mess. Plastic putty knives work well on the flat surfaces, toothbrushes on the mouldings.
2) Still wool the wood with more alcohol to remove any uneveness.
3) Restain-try a light stain and move to dark if you want.
4) Apply 2 coats of lacquer sanding sealer and sand between coats with
400 (or use the instructions on the can)
5) Apply 3 coats of lacquer, using 0000 steel wool between coats.
6) If you want a real shine try some of the polishing methods such as rotten stone or micro-mesh. This usually is reserved for the black Steinway finish however and it is a lot of work, probably not needed.
I did not use water based lacquer when I was doing this type of work (it did not exist) but I expect it will work well based upon my experience building violin cabinets.
Basilisk's comments should be heeded however do not be easily deterred from restoring. Uprights, unlike grands, usually do not have cracked pin-blocks since they are mounted to the wooden frame and do not circulate air as well. If the pins are worn in their holes, oversize pins can be purchased from American Piano Supply. Usually if every 3rd note in the base is out of tune after tuning it is a hint of a cracked pin block.
Email me if you have further questions above and beyond the finish (e.g. keys, hammers etc). You probably will end up with a better piano than you can purchase new.
Cheers Fritz