The Overriding Rule Is: There Are No Rules (At Least Not Formal Ones)
I love this rule! The concept here is that the D/s community is just that...it's a community...with a whole lot of diversity. As a community, it has no rules that go across the board; rather, there are conventions and a developing sense of ethics.
Our community largely is made up of people who are independent and who are more willing than most to live on the edge and to take risks. Further, because the D/s community's members have had the courage to be different from the "vanilla" norm, and because there is such an infinite variety of interests within the D/s bdsm world, they tend to have a much greater tendency to differ from each other.
What this means is that anyone (especially one new to the community) trying to lend a helping hand by suggesting a few rules to the community as a whole might well get that hand bitten off.
Nevertheless, groups can (and often do) impose minimal rules on their members to help things run smoothly. For example, groups that meet in public locations such as restaurants for their munches will typically have a "dress vanilla" rule for munches.
It is up to the group to let any newcomers know about its few simple rules. It is also up to the newcomer to find out if there are any.
Common Sense Things To Do
Even in the absence of rules, there is a generally recognized etiquette to these things. As a rule of thumb, simply try to follow the golden rule, be courteous and try to be helpful, rather than divisive. I've almost never had a problem doing this.
1. Courtesy Always
Merely because one thinks S/He is a Dominant, that is no reason to be rude, crude, demanding or blustery. In fact, those traits are hallmarks of wannabes. Saying please or thank you to a submissive who is not yours is a common form of politeness and chivalry. Similarly, a submissive thinking s/he can be as rude as she wants as long as his/her Dom/me allows it will soon find that s/he's being avoided.
2. Don't Piss Off The Event Organizers
Organizing a munch or other event takes a lot of work (a lot more than anyone who hasn't done it thinks), and putting it on is pretty stressful. Usually, a few dedicated individuals who are very experienced in the lifestyle put on these activities. Their opinions are given more respect than most and they are usually well known within their locality. Don't piss them off unnecessarily, unless you have a social death wish.
3. Keep Your Eyes And Ears Open And Your Mouth Shut
Especially for a newcomer to a group, even if s/he is very experienced in the lifestyle, the adage of listening a lot and talking little at first is a sound one. Learn the flow of things, and try to pick up on the subtleties of how things really work. D/s lifestylers are as human as everyone else is, and in some cases their egos may be larger than most. To take these things into account, and to be able to follow any "unwritten" rules, a person must first know they exist. The only real way to get that knowledge is to watch and listen.
This lifestyle is about the voluntary and consensual transfer of control and power from one to another. A transfer of control does not mean a transfer of feelings, integrity or of self-esteem. A dominant is not better than a sub, just different. An experienced player is not better than an inexperienced one. Someone who is sadistic is not better or more powerful than is someone who is a Dominant, but who is not sadistic. Too often, I see or hear disparaging statements about someone for these reasons. Personally, I find them offensive and my respect for the person making them diminishes.
5. Don't Touch
Fundamental rules of politeness are always acceptable, and this applies to handshakes, hugs, etc.. Handshakes are always ok, although many males will wait until the female offers her hand. Other forms of touching become more problematic.
Don't touch the Dominant. Many Dominants are sensitive about their personal space. I tend to avoid laying hands on arms, patting shoulders, etc. unless I know the other person well.
Don't touch the Dominant's submissive without the Dom/me's consent. This is the height of bad manners, especially if it is clear that the submissive does not welcome the touch. It's also the best way I know to create an enemy and get uninvited to parties.
Interestingly, the one time I had a problem with this was another submissive trying to pinch, tease and tickle my sub in a not-so-nice way. First I merely interposed my body. When she tried it again, I told her politely to stop. She stopped at that point. However, had she continued, it would have been very appropriate to have asked her Domme to control her sub's behavior. Such a request will almost universally have the desired result, as a Dominant is generally deemed both responsible for and in control of the sub's behavior and training.
Had it gone beyond that point, my options would have been to: (1) inform the hostess; (2) physically restrain the other submissive; (3) leave or (4) make a rather clear remark about a Mistress being unable or unwilling to control her submissive's rude behavior. Option (1) is the best choice; however, the host's handling of the issue from that point on is not subject to debate. Option (2) is a good way to get into a fight and/or get all parties involved uninvited. It doesn't matter who's right, you're disturbing a party and have lost control of the situation. Option (3) may have its advantages, but I find it difficult to leave due to someone else's rudeness; thus, it is generally unacceptable to me. Option (4) has a certain evil elegance and appeal, but may lead to the same result as option (2).
A person's toys are equally off limits, unless permission is asked and given. Most Dominants like to show off their toys, but the toys are theirs, not yours. Where permission to touch or use a toy has been given, return the toy in the same condition in which you received it. If it is damaged during use, the person using it should pay for getting it fixed or replace it.
6. On Gossip
Gossip is the most damaging thing people in the scene can do to another and to themselves. If I have a negative comment or thought about an individual, I try to keep it to myself unless I perceive there is a potential danger to someone else. When I hear negative comments about others, I tend to walk away.
7. Respecting Privacy
If I have seen someone in the scene, I do not acknowledge or even refer to the lifestyle in public unless they bring it up first. People are tight lipped about their activities in the lifestyle. I want them to respect my ability to respect their privacy.
8. After Parties
After parties are usually private parties put on by an individual or couple. They are by invitation only, and invitations are not automatic. Often, the host of a private party will want to observe a newcomer over a couple of munches to make sure he will be comfortable having the newcomer as a guest. For these reasons, one should never assume they are invited unless the host does so. Bringing an uninvited guest is also a big mistake. Invitations should never be solicited. And finally, even the existence of an after party should not be discussed or mentioned to newcomers unless and until one KNOWS the host has invited that person.
Many munches happen on a periodic basis at the same location (usually a restaurant or bar). It follows that if munch announcements specify vanilla clothing, there is a pretty damn good reason.
10. Following Directions
Many in the lifestyle are deep underground, and have no desire to be "outed". Their groups try to accommodate that desire for privacy, and accommodation can include avoiding too many cars in the driveway, staggered arrivals, etc. If the munch or meeting has door keepers or people who check invitations, those people will want to finish those tasks so they can do other things (such as acting as Dungeon Masters) or socialize too. It follows that if specific directions on parking, arrival times, etc. are given they may have been given for a very good reason. Further, people who exercise care in this area are generally looked on as being much "safer" acquaintances.
11. Drinks and Drugs
Drinking is usually discouraged, although drinking very moderately is sometimes acceptable. When in doubt, ask. Intoxication in any form is usually frowned on, and use of drugs usually (and should) result in an escort to the door. Remember that this is safe, sane and consensual activity that nevertheless is frowned on by a lot of people. Protect your group, protect its members, and protect yourselves. Keep drugs away from lifestyle activities. Further, from what I understand, and what common sense tells me, the easiest way for something in a scene to go seriously wrong is for one or both of the participants to be drunk or stoned.
12. Inquiries and Referrals
Frequently, I will get emails asking if I know a person in a particular city who is involved in the lifestyle. Even if I do, I will not give that person's name or email out. Rather, I will forward the request on to that person and let him or her decide whether to respond to the inquiry. If I want to meet someone or talk with him or her again, I will provide them with my telephone number or email address and let them get in touch with me.
13. When In Doubt, Ask
If I'm not sure about what's appropriate, I have no problems whatsoever in asking. People in the lifestyle like someone who's careful. Taking the care to make sure about things only builds that reputation.