Need to know if you will be given a diet sheet, some food that she is used to, worming info,whether breeder will be at the end of the phone if you have any problems etc. I'm sure there are more but that's all I can think of at the moment.
If he/she grills you about your lifestyle and wants to know everything, where puppy will sleep, how long left on own. I'd go for it. If they ask no questions or give you sparse info, I'd walk away.