[Crazy Dazz]

Firstly make sure you have a good battery, either by swapping, or jump starting from another big car.

Then first step is to try putting power straight onto the control point on the solenoid.
If that doesn't work then its either the solenoid or starter, (and you should be able to hear the solenoid)
If it does work, then work your way backwards.

In old AUs I have found problems with the key-barrel, and the transmission cut-out, bith solved by jiggling.