Help with collections

I have never done collections before, and was just told yesterday that I had to start doing them, but was not given any ideas on how to go about it. Any help or info you can give me on how to go about it or what to say would be greatly appreciated. I do not personally think that calling the companies and saying "hay, you are way past due, we need a payment, when can I pick it up" would get the same response I have given in the past, a firm click of the dead phone line.