1992 Dodge Caravan What can cause my van to run hot

Engine Cooling problem
1992 Dodge Caravan 6 cyl Two Wheel Drive Automatic

My van has been running very hot lately, but not to the point of overheating yet. I replaced the thermostat and it still runs hot. I noticed that the fan that sits behind the radiator does not come on at all. I have been told this could indicate anything from a bad water pump to a bad cooling fan. I do not notice a leak from the seap hole in the water pump but I am also battling an oil leak so I may not be able to tell the antifreze from the oil. Is there any way to tell exactly what coud be wrong before I go replacing random parts at my own expense? Trying to repair myself due to financial issues. Am semi mechanically inclined. I figure, if I can replace a starter, I should be able to do this.