Safe
"Safe" means that we take care of each other as best we can, that no matter how we want our scenes, however gentle or rough, we do them in ways that do not injure our partners. "Safe" means that we take the dangers of sexually transmitted diseases seriously and use our best efforts to minimize those dangers.
What can you do? Educate yourself. Learn as much as you can so that you can do safe scenes. That means read books, take classes, and ask others about specific techniques that interest you. Want to learn to use a cane? Ask an expert. Want to swing a flogger? Practice first on a pillow.
Whether you're driving a car or tying somebody up, safety should always come first. It's especially important to not let your desire rule your good sense, so think about the specifics of your scenes outside of the scene. "Don't think with your groin."
Sane
Power exchange is about trust -- trust that the person who has the power in a scene will use it responsibly. If you are the Top then it is up to you to use the power your Bottom has granted you in a respectful and sane way. Your Bottom has given you a gift of trust, and you are honor-bound to repay it with good judgment.
If as the Top you are so involved in your scene that you can't make good judgments, then you are not in control of yourself, and you have no business being in control of someone else. Sanity is about control, and self-control comes first.
Consensual
Everything that happens in a scene between people must be acceptable to all concerned. If you aren't sure that your partner has consented -- has said 'yes' -- then you need to talk until you are sure.
The best way to get to 'yes' is to make sure that 'no' is an equally acceptable answer. This holds true in every situation, whether asking someone for a phone number or negotiating a scene. The less pressure you apply, the more likely that a 'yes' will come and will be a sincere answer.
It's dangerous to play with someone who has said 'yes' for the wrong reasons. You can quickly end up in a situation that is neither safe, sane, nor consensual. To protect against this, refrain from pressuring anyone, and if you feel you are being pressured, set limits and stand by them. You should always feel free to say 'no.' Consensual means that you are sceneing because you want to, with someone who wants to, that everyone involved is willing to go ahead with the scene. If you are in the least bit unsure, stop and talk.
The time to clarify consent is before a scene, not after.
