How many miles on it? At the very least change the fuel filter.

a) From my experience, the plug wires don't last too long. Consider yourself
very lucky if none has failed yet. They are not very cheap, but replacing is
good insurance, especially if you are planning a long trip and don't want to
become a victim of an unscrupulous mechanic somewhere. If your plugs have
not been changed in the last 50,000 miles, I would change them at the same
time, especially if you don't even know what type they are.
b) Follow the user's manual instruction for scheduled maintenance. Working
from memory:
1) Change coolant (at least check concentration)
2) Basic brake service: look for leaks, check brake pads thickness, have a
look at the rotors, grease caliper sliders. Some will argue with this, but I
would replace the brake fluid while at it.
3) Check differential fluid level
4) If you haven't done so in the last 30,000 miles, replace the transmission
fluid
5) If this is an AWD or a 4x4, replace transfer case fluid and check front
differential fluid level