Business Software integration Advice for start up business

Software integration using Xero, Woo Commerce and Pipedrive - general business advice from known successful experience. We are setting up a separate start up business with online sales and need help to scope out interaction and software priority on customer and prospect data, product data and online order handling. The output from this first part is to give general advice and a scoping written document on how the software systems will successfully integrate with each other.
Successful completion of this initial project will likely lead to further project work to develop and actually be involved in the integration of the software.