This PTV will give some precautions to take and what steps you should take before entering this fetish. For example, know their limits so you don't push him past his/her limits.
Disclaimer: Blackmail IS illegal. What slaves like about blackmail is the loss of control and power. They want to feel trapped and overpower and they feel like blackmail is the only way to feel that way. Don't jump into blackmail if you don't know what you're doing and you're new. Blackmail is a federal crime. There can be serious consequences if things go wrong. Many slaves have recently enjoyed luring dommes into blackmail and turning around and turning them into authorities. Some slaves are actually into blackmail in the beginning but they change their mind or the domme goes too far. Just remember your limits and your slaves limits, trust your instincts and know the slave before decide to participate in blackmail with him. Use your best judgement
I am not a lawyer and cannot give legal advice or tips.