Will Not Start

I have a 84 buick regal 231 v6 3.8l....
When I try to start the car, it trys to turn over but nothing. I was wondering if someone could tell me the process that I should go through to eliminate possabilities. It has been acting as though it dosent want to start, then starts prior to it not turning over at all now...???

First thing to do is check the battery. With the car off turn on the headlights for 30 seconds to get rid of any surface charge. Check the battery voltage, it should be 12.6. If it is less than 12.2 it is time to get a new battery. Next check the connections to ground and to the starter. Make sure all the battery connections are clean. Third check to see that the (purple?) wire on the solenoid is getting 12 volts when then key is in the crank position. If it is not then it is likely the ignition switch. If it has 12 volts and the large wire has 12 volts then it is either the starter or the solenoid. If the solenoid clicks but nothing happens then it is a bad starter, if nothing happens then it is likely a bad solenoid. I would replace both since they are pretty cheap.