Negative cable, Positive cable from the battery to the solenoid, Positve cable from the solenoid to the starter..                                                                                                                                                             First take your DVOM and connect it across the battery, check battery volts, should be 12.6....could be a little higher if the car was just run. With meter connected crank the car and see how low the voltage goes....shouldnt loose much more than a volt if everything is good. Then take your DVOM and connect one lead to the battery positve terminal, connect the other to the starter positive. Polarity doesnt matter for this test with a DVOM. Crank the car over and see what the meter reads. The meter will show you the amount of voltage lost over that cable when starting. Repeat the test for the negative cable. You could even do a test from the solenoid to the battery, then from the solenoid to the starter, to narrow down the problem if you think think the positve side is your problem....even test just the solenoid. You shouldnt be seeing anymore than .6 of a volt across either the positive or negative side of the circuit, a .1V drop would be more ideal. Most of the voltage drop you see in a good working starting circuit should be being used up by the load...which is the starter. I would also suggest doing the test when the car is giving you the problem and also disable the fuel....no need to actually start the car. Keep cranking time to about five seconds.  If you do a google search about voltage dropping a starter cable you can find some very detailed instructions on how to do it and the theory behind it. Hopefully my explanation is enough to get you through it.