You can do it piece by piece, you don't have to reno all at once. You want to have it inspected and make sure the foundation is good. Get the roof inspected, make sure there is no leak there or in the ground (water can run off in a way where it can collect around the house and seep into the basement..which is bad). You want to look for cracks in the walls and ceilings which can indicate instability. If it were me, and I've looked for homes made during the time you said, I'd do foundation, roof, electricity (if it needs rewiring) and plumbing, first. Later, furnace, water heater, floors, windows, fixtures..etc. If you have to live in it while you're doing it, then obviously water heater, furnace, and plumbing have to be in place.
Everything you can do yourself..do it. It'll be cheaper and it's not hard to learn a lot of it. Electric, putting in a new furnace (not hard, but not something you want to be wrong about..you could kill everyone) and similar jobs you can hire someone else to do.
