* Pól Ó Baoill: This is a common and fairly straightforward approach. "Pól" is Paul, "Ó" indicates descent, and "Baoill" is a common anglicisation of Boyle.
* Pól Ó Baoghall: This version uses a slightly more traditional spelling of the surname.
The best option depends on context and personal preference. There's no "wrong" answer, but these two are frequently used.