1996 Toyota Camry Starting the car

The car sat for several months and it would not start. After cleaning the battery cables and the battery posts and using a charger I was able get it started; only after continued trying. It would turn over a few times and then the starter or the solenoid would begin clicking. After repeated tries and putting some gas on a plug it started and I ran it for 15 minutes. Now after a week or two it won't start, it just barely turns over and then starts clicking. What should I check next?

Thanks