This is a little different than most BDSM principles like Safe, Sane and Consensual (SSC). The truth is, I feel, SSC just isn't enough. It is too basic and not meant for long-term BDSM relationships. Instead, I propose a new tenet. Care, Consent, Communication and Control.
1. Care is first because if you care for someone, genuinely care for someone, then you will look out for their best interest. You want to learn about their history, hobbies, interests, dreams, aspirations and their quirks. You listen and pay attention to their needs, injuries, limits and conditions in a scene. You look at that person with care and love, which is something the other person can feel. Care builds trust between two playmates or partners and that trust is the foundation to a scene and to a relationship.
2. Consent. BDSM is not your everyday activities and most often it involves two or more people. Hence it is important that everyone involved agrees to be part of it. Some resistance, edge or 'consensual noncensent' plays may require actual consent forms signed before a scene. Regardless, there must be verbal or written consent before playing out a scene.
3. Communication is fundamental to BDSM. It involves negotiating a scene between playmates, learning about one another, relationship building, receiving feedbacks during and after a scene and etc. Being a good communicator is integral to a stable relationship, whether vanilla or BDSM. Lack of communication may break a vanilla relationship; lack of communication in a BDSM scene or relationship can cause severe injuries. There is no such thing as over-communicated, so talk it out.
4. Control means many things in BDSM depending on what you are into. It can mean power for those in control of their submissives or it could mean mastery over one's play elements, I.e. Whips, suspension, mindfuck among others. Here, I will also add that it means mastery over one's physical, mental and emotional states. To be in control means one is free of any distractions that could influence one's focus on the task at hand, I.e., drugs, alcohol, grief, anger and extraordinary stress, and possess the necessary skills and knowledge over one's tools and techniques. We are all very fragile, mentally and physically and being in control helps us protect only ourselves, but those with us in a scene or relationship.
Ultimately, BDSM is a form of giving/receiving such that all parties involved can take pleasure from, even if it involves pain. If you keep that in mind, chances are it is hard to go wrong. Anything and everything is open for discussion. Don't make assumptions and remember, if things don't work out the first time, try again and again after feedback.
Have fun. It is what keeps us coming back for more.