Starting problems

Clarify first the symptoms. Do you hear a single kind of loud clunk from the starter each time you turn the ignition switch to "crank"? And it will eventually crank if you cycle the ignition switch enough times? If that's the case, that is a very common failure of the solenoid contacts. They can be replaced for 20 bucks but most people just replace the entire starter.

If it tries to crank but too slowly and the lights dim at the same time, (helpful observation, by the way), that sounds more like loose or dirty battery cable connections. If the battery needed to be recharged, ... Why? Could there be a problem with the alternator? It's a little early for the mileage you listed, but worn brushes are pretty common. They can also be replaced separately. To test for a charging problem, use an inexpensive digital voltmeter to measure battery voltage while the engine is running. It must be between 13.75 and 14.75 volts. If it stays around 12.6 volts or less, we have to diagnose the charging system.