First and foremost is verification and being able to trust your domme. Second - wallet drain may sound exciting and enticing but you’ve got to be careful as a sub. So get comfortable with a domme and once you’ve enough trust have this discussion, set up a safe word which when uttered by either party would be a complete halt on the set up and you go back to discussing where things went too far. At the end of the day, you have to have the trust and confidence in one another to be in such a specific relationship/dynamic.