First, acknowledge the effort they gave towards the work to make them more receptive. Then, present your ideas and suggestions. Finish the conversation with one last acknowledgement or appreciation for their efforts.
"Blessed are you whose worthiness gives scope,/Being had, to triumph; being lacked, to hope." This was written by Shakespere. There are more examples in the article.
You could say something simple like, "Hi. Thanks for using our book store. To get a better experience with our book store, please join/ask our customer support any questions you...
If you want your clients to leave great reviews for your service, try asking them something like: "What was the most valuable thing you got? What was your biggest insight?...