Depending on how much and the type of use your vehicle has will indicate the preventive maintenance that may be required.
Check you vehicle owners manual for recommended maintenance schedules and the work that should be completed at those intervals, this will let you know what needs to be done and when.
Periodically give your vehicle an inspection so that you can catch anything that looks odd or different. Make sure all your lights are working, check your tyre pressures and listen for any strange sounds inside or out.
Remember to check your fluids, antifreeze, power steering, coolant, wiper fluid using either the supplied dip stick or the level checked on the reservoirs.
There are many other simple checks that you could make :-