Help me save her!

I've had this clone for approx. 2½ weeks and have been trying to keep her alive. I know It hasn't had the proper lighting from day one and I've been working on correcting that. But it's experiencing other problems, i.e., yellowing leaves, brown spotting on the leaves and more than likely some other crap I can't diagnose.
Please have a look and give your experienced opinions. It would be much appreciated.