How to trouble shoot starting system 98 ford crown victoria

Also check to see if there is power in the start wire form the ignition switch, the wire is a white wire with pink stripe, most likely not a common problem, but still something that could go wrong. this wire will feed the starter relay under the hood...

Check battery terminals are clean and firmly connected,
Check chassis ground connection is in good order,
Check power is available for headlights or other vehicle lights etc,
Check starter power cable and solenoid engage control wire is securely connected to starter motor,
Check +12V is available at the starter solenoid engage control wire when the ignition switch is held in the 'Start" position - (if not, look for a faulty relay or fuse in the start circuit),
Check starter motor runs when +12V directly applied to the starter solenoid 'engage' control terminal.