I'd recommend you look at the guidelines rather than asking on here for a more complete answer.
Short answer is that vaginal deliveries are preferred unless there is an indication requiring a C-section.
If there is no indication for a C-section as per the guidelines, then a vaginal delivery should be done.
"Patient preference" is not technically an indication for a C-section.
Vaginal deliveries have lower risks and potential complications vs. C-sections in the context of a C-section not being indicated.
Vaginal birth after previous C-section (VBAC) is risky, particularly risk of uterine rupture.
As for how to approach a patient, I'd just follow the same lines of communication that you usually use...
>Why do you prefer a C-section?
>What fears do you have regarding vaginal delivery?
>Are you aware of the epidurals available to relieve pain during labor?
>Inform about the risks of C-section and vaginal delivery
>Etc.
Disclaimer:
1) I'm a med student and these are just some of the points I remember from my rotation.
2) This information is not intended to be used for diagnosis or treatment of medical conditions. Always consult your doctor.