Truck won't start! Help please

If your testing voltage on the battery to see if its good, testing it without load can fool you, turn on the headlights and the heater fan and interior lights, now test the battery voltage, it should be showing good voltage with a load on it. I found this to work for me many times helping friends and relatives, if it still clicks and does nothing else....most likely bad connection/wire or bad starter, more specifically the relay/solenoid on the stater, they click closed making the high amperage connection to turn the stater motor, after so many connections they get to pitted from the electricity arching and stop working, sometimes if you keep trying it will work once in a while. Your alternator might not be charging the battery....but thats the last thing you should check, especially if your battery is older.