Depends what level of service your car needs,
Oil/Filter
Air Filter
Pollen Filter
Fuel Filter
Plugs
Coolant change (every 3-5 years depending on what coolant is used)
Brake Fluid Change (every 2 years)
Cam Belt Water Pump
Brake pads/discs
all of the above may need changing, I would say if the history of the car is unknown then I would be changing everything listed, except the brakes unless they need to be.