More Mystery ...

Me being my wimpy self, after finishing And Then There Were None I decided that I didn't want to read another mystery again for a long time. A day or two later, however, I began to feel less sure about it. Then I watched Marple: The Body in the Library on PBS and completely changed my mind. I now want to read everything Agatha Christie. From the great to the just ok - I want to read them all. Not sure exactly where I should start, though. Any suggestions?