Won't Start - Clicking Noise

When I turn the key to start my 96 K1500, all I hear is a clicking noise. Usually I can wiggle the key around and it will eventually start. Any ideas as to what is causing this?

That sounds like a bad solenoid on the starter.
If you have a voltmeter, put it on the solenoid large cable from the battery and click it to read. You should see battery voltage. Then put the meter on the output of the solenoid where it bolts to the starter connection. When you click it if you don't see battery voltage, the solenoid is bad. If you do see battery voltage tneh it would be the starter failing.
Is the battery good and charged? Do you see 12.0 volts or higher?

Or a loose connection. Check your battery cables, clean them and the posts. loosen, move around and tighten the cables at the other end, check the connections of the large cables at the starter.
Bob B