Fluids for a truck that sits a lot?

I just purchased a 96 Chevy S10, 4cyl, 5-speed with 180,000 miles on the engine ($500, so difficult to pass up the deal - it's in excellent shape). It's a utility vehicle for a seasonal business, so it will sit a lot and get few miles annually.

Any suggestion for the best fluids (oil, coolant, etc) or any useful additives or should I just change everything annually before I park it for the winter?