I just bought an 85 ford bronco. Previous Owner mentioned a new alternator, starter, and solenoid. I brought a battery with me, and it fired right up. On the way home, it died, and the battery was drained so much that I needed to jump start it...this after only 4-5 miles. It made it home with me keeping the RPMs up. It seems to me that the alternator isn't charging the battery enough. What wires do I connect to to be sure the alt is charging the battery?

Check the starter solenoid and the connections from the battery to ground, battery to fusebox, ignition key switch, neutral or park safety starting switch, solenoid, and solenoid to starter. Make sure you have ignition key switch wires connected to the solenoid - without them - the solenoid can not close to send 12V to the starter.

try jumping your battery and see if it starts

Is it getting fuel? try spraying some starting fluid in the carb, and see if it'll start!
if so, fuel pump may be bad!

If a manual transmission you can try push starting it . Take the belts off and see if it cranks then . Pull out all spark plugs and attempt to crank it over .

Check the fire on the swicth wire on the starter

The positive battery terminal cable goes to the input side of the solenoid along with another smaller wire that powers the rest of the car. The smallest terminal has one even-smaller wire that operates the solenoid from the ignition switch 'start' position. The output side has another cable which goes to the starter power terminal.

bad ground wire on battery,if everything dims in vehical while turning ignition and I mean from bright to almost nothing thats what is wrong,if not some have a small fusible link to solenoid that blows or gets disconnected or corroded.
your ground wire will look fine but maybe have broke or corroded connection inside or on ends,had same problem with more than one vehical.easy check use a jumper cable from negative on battery to alternator bracket and give it a whirl.

check on your ignition switch and its harness,make sure you have a contact. and re check those connections youve mentoned. Be sure your negative groundings going to the engine and the body are tight and cleaned.
It will really be a long night to trace all those weak connections. trace the positive connection from your battery going to your starters and going to your alternators.
And be sure that all fuse and relays are working.
Hope i have fix your problem.

Starter Bendix solenoid. Change entire starter. If planing to keep car long time buy a lifetime warranty one.