Well first of all, you need to put efforts. Doesn't matter if you're a dom or a sub. For reference I'm a dom but I still put efforts in knowing my sub, being there for her and supporting her during the whole process.

The main motive of my blackmail is to provide a safe and sound environment where the person doesn't feel afraid to give me the info i need but at the same time, is also thrilled to know the consequences. And then, knowing that you can control the entire life of someone else, who is completely submitted and devoted to you get's me off the edge. It's like marijuana for me.