A couple of people have brought up the topic of moderation. Perhaps Navindra already has ideas about rules, but I've started a new thread to discuss it. For reference, I'm quoting the Pianoworld rules (I think these were written by VerticalScope, as they seem very generic):

A lot of this is legal stuff. Here are the important parts as regards users and moderators:

You may not:
• Restrict or inhibit any other user from using and enjoying the Web Site.
• Use the Web Site to impersonate any person or entity, or falsely state or otherwise misrepresent your affiliation with a person or entity.
• Interfere with or disrupt any servers or networks used to provide the Web Site or its features, or disobey any requirements, procedures, policies or regulations of the networks we use to provide the Web Site.
• Use the Web Site to instigate or encourage others to commit illegal activities or cause injury or property damage or interfere with business interests or contractual relations of any person.
• Gain unauthorized access to the Web Site, or any account, computer system, or network connected to this Web Site, by means such as hacking, password mining or other illicit means.
• Obtain or attempt to obtain any materials or information through any means not intentionally made available through this Web Site.
• Use the Web Site to post or transmit any unlawful, harmful, threatening, abusive, libelous, flaming, hateful, offensive (whether in relation to sex, race, religion or otherwise), defamatory, obscene, vulgar, harassing, pornographic, profane or indecent information of any kind, including without limitation any transmissions constituting or encouraging conduct that would constitute a criminal offense, give rise to civil liability or otherwise violate any local, state, provincial, national or international law.
• Use the Web Site to post or transmit any information, software or other material that violates or infringes upon the rights of others, including material that is an invasion of privacy or publicity rights or that is protected by copyright, trademark or other proprietary right, or derivative works with respect thereto, without first obtaining permission from the owner or rights holder.
• Use the Web Site to post or transmit any information, software or other material that contains a virus or other harmful component.
• Use the Web Site to post, transmit or in any way exploit any information, software or other material for commercial purposes, or that contains advertising.
• Use the Web Site to advertise or solicit to anyone to buy or sell products or services, to cease using the Web Site, to visit another competing Web Site, or to make donations of any kind, without our express written approval.
• Gather for marketing purposes any email addresses or other personal information that has been posted by other users of the Site.

Moderators
Acting as a moderator of a forum on Forum.PianoWorld.com is an unofficial, volunteer role. Moderators are not employees, contractors or agents of Forum.PianoWorld.com or PianoWorld. PianoWorld and Forum.PianoWorld.com are not responsible for actions or inactions of moderators.
If you act as a moderator, you agree that:
• You will always act in good faith as a moderator. You should always maintain a calm and cordial demeanor as moderator.
• You will not accept any gifts, favors or other compensation from third parties in connection with or related to your actions as a moderator.
• You should not promote or advertise any particular product, brand or service, and should remain impartial.
• You will comply with these Terms and Conditions of Service, along with the moderating guidelines and content policies of PianoWorld made available to you from time to time. You will take appropriate action whenever you are notified of content that violates PianoWorld policy or promptly escalate matters to PianoWorld for review. To the extent you are uncertain about what is the appropriate action in particular circumstances, you will contact PianoWorld.
• You are not authorized to act on behalf of PianoWorld and may not represent to others that you are authorized to act on behalf of, or otherwise bind PianoWorld.
• As a moderator, you may receive or have access to confidential and/or non-public information. You will not publish any of this information online or share any of this information with third parties. You will keep this information secure and will protect this information from being accessed or seen by others. You will not use any of this information except in connection with your role as a moderator. If you believe any of this information in your possession has been accessed inappropriately, you will promptly contact PianoWorld. You will continue to comply with the provisions in this paragraph, even after you are no longer a moderator.
• PianoWorld may revoke your right to moderate at any time, for any reason, and may in its sole discretion, overturn any action or decision that you make.

Since I used to moderate at Reddit's r/piano, I thought you might like to look at the list of r/piano rules too:

Common generic questions should be asked in the 'There Are No Stupid Questions' post. The following list of commonly-asked questions have been linked to the appropriate sections of the FAQ:

How much is my used piano worth?

What is the make or model of my used piano?

What's the name of this song?

Can someone write out the notes to this song?

How do I find sheet music to this song?

What are the chords to this song?

What's a good keyboard / piano to purchase?

How do I get started playing piano?

Am I too old to learn?

If the FAQ doesn't answer your question, you can ask your question as a comment in the 'There Are No Stupid Questions' post.

No low-effort images, memes, jokes, or context-less images. Low-effort and meme image posts are better suited to /r/classicalmemes, /r/pianomemes, or /r/musicpics. Pictures lacking context or details are subject to removal. Please provide as much information as possible to foster good discussion.

No basic tutorials or Synthesia "tutorials". The amount of Synthesia "tutorials" or beginner song tutorials we get is too much and would overtake the subreddit if we allowed them. Very basic theory/song/other tutorials are better suited to /r/learnmusic.

No generic piano music videos / playlists. E.g. "1 hour of sweet ambient piano"

No spam, advertising, low-content blog posts, etc. See reddit's definition of spam here. Spam includes posting too frequently, posting mainly links to your blog / Youtube channel, low-content blog posts, etc. If you're unsure if your post will be considered spam, please contact the moderators before posting.

Be nice to each other. Comments that contain personal attacks, hate speech, trolling, unnecessarily derogatory or inflammatory remarks or inappropriate remarks (e.g. commenting on someone's appearance), and the like, are not welcome and will be removed. See reddit's content policy for more examples of unwelcome content.

So all of that is just for reference. Personally, I think one or two common-sense rules (like "be nice to each other" and "no spam") might be a good place to start, and you can add to the rules as necessary.