Keep "reality" out of it. Unless both of you specifically agree to it ahead of time, BDSM play is not a proper occasion to "punish" someone for a "real world" offense. Unpaid parking tickets, dirty dishes left in the sink, and so forth get handled outside the BDSM play.
The more empathy you have, the better you'll be at this. If you reasonably and safely can, experience something yourself before you do it to another person.
1. Prepare for emergencies. Have needed supplies close by, including a first aid kit, a fire extinguisher, and flashlights. Take training in First Aid and CPR at least once a year.
2. Play with a "silent alarm" in place. When you play with somebody new in private, tell a trusted friend where you'll be and who you'll be with. Make sure, diplomatically, that you tell your prospective partner ahead of time that you will be doing this, and encourage him or her to do the same.
3. Negotiate what you'll do ahead of time. This is not the time to have a mismatch of expectations. Handle such matters as sexual behavior, safer sex precautions, type and degree of bondage, physical and emotional limits, and so forth before you play. Stay within these limits while you play. If your session goes well, there's always next time. Check in with each other afterwards, perhaps the next day. Discuss what did and what didn't work, and what you might do next time.
4. Agree upon a safeword or two. These are special phrases used to indicate that the activity "really" needs to be slowed, changed, or stopped. Refusal to honor a safeword is very serious misconduct; it can even be a crime.
5. It's a good idea for the dominant to "check in" with the submissive several times during the session. (Sometimes submissives find it difficult to use their safewords, even when they should.) One good non-verbal check-in is for the dominant to give the submissive's hand two light but firm squeezes. If the dominant gets two squeezes back, it means that the submissive is basically all right.
6. Avoid toys that have sharp edges or corners. Instruments used for spanking, whipping, and so forth should be carefully rounded off.
7. Start lightly and build slowly. A too-rapid increase in the physical or emotional intensity of the play is the direct cause of many problems.
8. The submissive can use the "one to ten" technique to indicate they're ready to feel a paddle or whip stroke, and its intensity. "One" is a feather-light touch; "ten" is a full-power stroke.
(CONTINUED)