You will have to call dozens of companies before you get much response, so don't worry to much about blowing the first couple.
It might be a good idea to prepare a list of questions you expect to get and what you will say. And if somebody hits you with one you didn't expect, write it down and work out a better answer later.
The only thing you really need is to work out how much you will charge ahead of time. If you get somebody that claims to be getting the work cheaper already, tell them they are getting a good deal and move on. The better small buisness guys will haggle you down to nothing if you let them.
Jay