In the following order: Battery connections clean/tight, connections at solenoid clean/tight, connections to ground clean/tight, connection from solenoid to starter clean/tight? If in doubt, disconnect everything in order, and hit it with some emery cloth or sandpaper, then reassemble and tighten properly. It's something simple, usually.
When was the last time this car started? It's a Ford, they're pretty straightforwar d (all I've owned since I got my first car in 93). lol