One of the "traps" associated with being the master in a BDSM relationship is too much emphasizing the expectations and fantasies, without paying attention to the other person. We think "Master" and immediately fantasize about power and control and exercising those desires, without acknowledging the reality: we are not the only person here, we are not an actual master and we assume that "Master" means just that, and the other person is just a replaceable prop that we are playing with. And then, to make matters worse, some have the potential to get angry when got an objection - in this case a perfectly reasonable, and react as such.
Lesson One: The Master Is Not (Really) In Charge
It doesn't need to be this way. Not at all, not ever, and especially not with someone who trusts you enough to be "in charge" of a scene. Because it must be emphasized repeatedly: as a Master you are not in charge. At best, you are a co - author in this BDSM story. As such, you need to be aware of your partner just as much as yourself.
It's easy to power trip as a Master during a scene, and there are altered states that may happen to you (known variously as Dom-space, Top-space). Now the power dynamic is important here. As a Master, you are deriving your sensual experience and potency from being in that role. But being a Master isn't just calling yourself Master or Mistress and flogging someone. In fact, being a Master might not include any traditional elements of master play at all; it can reside in a look, a facial expression, a heavy breath or a selection of choice words that evoke a sense of power, strength and authority.
But, communication is the priority. A good Master knows when to listen, when to take action, and when to step back. This is just as important to you as it is to whoever you are with in the scene, if not more so. The Master is the one who has to be in control not only of the scene, but of them-self ... at least for the duration of the scene. Your play partner is the one who is trusting you to be a safe person and to create a safe space for them to express their own pleasures, their own pain, their own desires and shadows. They are trusting your sense of control over yourself.
Self Control and Safety as a Master
The first part of this consideration is safety.
There's the obvious side of safety in kink and in sex in general: the submissive partner - whether known as a bottom or other term - is trusting you with their physical safety. There is a whole associated cluster of both power-triggered arousal, euphoria and fear that comes packaged in with it. Even as a Master you can, and likely will, experience fear, anxiety, concern, and awkwardness. This is normal. It will happen to you eventually.
Has contraception and safer sex been discussed? What tools will you be employing for this specific scene and how can the scene be as physically safe as possible within those boundaries and within that context? While both partners are responsible for ensuring the scene proceeds faithfully and properly, the Master needs to be the one to remember to check in regularly during the scene, using the agreed upon safewords and other methods of communication that were set up before the rope was even taken out of its bag. (Seriously, before you even try to set a scene, you need to know how to end it. Communication is key, even if a ball gag is in use.) Because once the BDSM scene begins and emotions are flying around, endorphins pumping through the blood, and both of you are lost in your respective roles, things can sour pretty quickly if both parties forget what they are doing. As a Master, you must be fully aware of your actions and your partner's reactions. Always.
There should also be safety scissors if necessary, such as if you are doing any sort of bondage play, just in case either partner start feeling a lack of circulation in their limbs - or need to be cut / untied immediately.
You may have heard the phrase "safe, sane and consensual," when hearing about kink. That's a good one, but let's discuss also RACK.
RACK stands for risk - aware consensual kink, and is often used to describe situations in which some risk is known. Perhaps your play partner is under treatment for depression. Perhaps they get panic attacks every now and then, and while they are eager to play, want to talk about what you can do if they start getting a panic attack in the middle of playtime. Or - more visibly - perhaps you have back pain you need to adjust for, or an old ankle injury. Other aspects of risk are included as well; with things like flogging, or hot wax, or rope, where pain and pleasure are blending together, it's very possible to forget that you are in fact causing harm for the sake of ecstasy. There's a line there can be crossed very easily.
There are seen prospective Masters who think that all you need to be master is to shout at or threaten your partner, and have gear like chains, rope or a gag.
An experienced Dom will be familiar and comfortable with their toys and tools. They will observe their subs and act according to what makes them feel comfortable. Masters may shout at their partners, certainly, but only within boundaries the partners set together.
This goes for faults just as it applies to Masters knowing what their skills and limitations are. Dominance contains all that too. Know thyself, the saying goes, and a Master should at least be on the journey to know themselves and what they want in order to best provide, give, and nurture their submissives. If you're interested in becoming a Master, you do not need to have all the answers, but you do need to be willing to explore where your baggage came from, and what you can do about it. You need to take responsibility for your own actions. Will you make mistakes? Yes, you're a human; people are going to make some mistakes along the way, sooner or later. That's part of gaining experience and leveling up.
Now, this also means that if there are risk factors or hard limits you have, that you discuss them with your prospective partners as well. Just because you are a Master in a relationship does not mean your partner does not have agency or power. What would happen if you are sick? In hospital? Do you want your partner to be able to look you in the eye and tell you something is wrong or that something you did or said bothers them? Does the submissive partner - if the submission is maintained outside the bedroom as well if - have the agency to make the choice to call after you, to send you a card, to pay any shared bills? If you are sick and cannot meet a play date, is there any protocol or ritual to deal with that? Is there a protocol that will help you and your partner feel secure? Does the submissive have the agency to leave you for another Master if your time with them is not to the benefit of both parties?
All People Do D/s a Bit Differently
The third key thing to keep in mind as a Master is to be aware that people are all different.
Even if there are two Masters using similar tools (say, both use flogging) who come from similar backgrounds, they are still two distinct people. There are many types of dominance and submission play, and Masters also have different flavors, even if the tools they use are the same. What bothers one may not bother another. What may be one person's hard limit may be a non-issue to someone else, and so on. What that means is that you need to start at ground zero with communication and introspection for each and every partner you play with.
One example of variation is what the Master is called and what language they might use. Some Masters prefer the use of particular terminology to address them, and the terminology itself may have particular meaning. For example, a Master partner may insist on being called "Sir" - and with the first letter capitalized to symbolically represent the power dynamic when in scene or discussing a scene. Another Master may be simply "Jane," while another Master will not use their given name at all during a scene but instead a title. Some Masters pay very close attention to how some titles may be loaded with gender norms and expectations, and/or with racial supremacy undertones. "Master" can carry very different connotations than "Mistress" and unpacking those titles and feelings about them may be useful. Feel "Sir" is too masculine for you and want to go by "Ser" instead? Sure. Really like how being called "Your Majesty" makes you feel? Go right ahead. Don't want to use an honorific at all? Sure. Be your awesome self.
This goes for tools too. Just because a Master might use one particular tool does not mean every Master who uses that tool takes the same approach. For example, using rope can be done with more aesthetically pleasing ties and acting stern, but loving and gentle. Alternately may be something more primal there. The key is to be both on the same page, to have been communicated about what works for each of us, and we've learned how to treat each other in scenes.
Being a Master is an evolving thing: it involves ongoing communication, reflection and adjustment.