I think the animesuki forum rules are pretty comprehensive, so I'm gonna copy-paste them here. They seem to (for the most part) be good rules of thumb. I'm inserting commentary where our views differ from theirs, in the form of double-braced {{ entries }}
Note that I'm not a mod or admin, I'm not posting these as gotwoot rules so much as good examples of rules of thumb to follow.

# Do not ask for licensed anime or manga
As described in Fansubbing and Licensing fansubs are technically illegal as they breach copyright. However as AnimeSuki.com does not wish to be associated with piracy, discussions about unlawfully getting licensed anime or manga or even DVD rips are not allowed. This means it is not allowed to post links to sites with such licensed material or ways to obtain it illegally, or ask for links or instructions to be emailed or PM'ed to you. Threads which break this rule will be either closed or simply deleted.
{{ This rule doesn't really apply to us, since gotwoot's directly affiliated with aone, which subs select licensed anime titles }}

# Do not ask for other illegal materials either
Obviously discussions about getting any other illegal materials, such as Ripped Music CDs (such as Anime OSTs), ROMs, ISOs, Warez etc. are not allowed either. Threads which break this rule will be either closed or simply deleted.
{{ This also doesn't apply to us as much. Anime OST's are generally acceptable on gotwoot, the latest Metallica CD or GBA rom or longhorn iso is generally not. }}

# Do not ask for when stuff will be released
Do not ask when episodes will be released. They'll be released once the fansub group is finished with them. All your whining will do is irritate fansub group staff and make them leave the scene. And that will mean even slower releases or none at all. So just have some PATIENCE. Threads which break this rule will be deleted.
{{ yeah ... that's a good rule. }}

# No Spamming
You are not allowed to post the URL and/or name of any website which you are in any way affiliated with to new threads or as replies to threads where mentioning that URL is not relevant and/or the only reason for posting seems to be to advertise the site or product. Offering products for sale or trade is also not allowed and considered spamming. This rule does not apply to signatures. If you are not sure, please ask first by contacting the one of the Administrators or Moderators.
* "Army Building" games spam
Posting links on the forum to any online "army building" games like those found on outwar.com or kingsofchaos.com will result in an immediate ban, without warning.
{{ notice, this basically applies to things where you get something by attracting people to click on your link, or generally advertising for something. Spam in its pure form doesn't have a whole lot to do with frequency of posting, but more to do with the nature of the post. }}

# No insulting and/or harassment
Insulting and/or harassing other forum members on the forum or through the PM feature is not tolerated. Any inappropriate language will be removed and if threads turn into flame wars they will be closed.
{{ of course there's some flexibility here ... but remember the aphorism "Fighting over the Internet is like competing in the Special Olympics -- even if you win, you're still retarded" -- if you must flame, flame gently and in a thoughtful manner. }}

# Do not cross post or post the same message more than once
If you want to post a message, do so in the forum that is best suited for it. Do not post it to existing threads which are not relevant to your message and post it only once.
{{ so if your question is about tsukihime, post it in the general anime forum. If your question is about read or die, use the read or die forum. If your question is about where the readers are from, post it in general discussion, but not general anime and definitely not the gungrave section. }}

# Do not post nonsense
If you don't have anything to say in a thread or don't know the answer to a question, please do not post that you don't have anything to say or do not know the answer the question. Posting just to "bump" a thread and posts such as "I agree", "OK" and "Me too" are also considered nonsense posts and may be deleted. You are not required to reply to every single thread in a forum. Please only reply if you have something useful to add to the thread.
{{ I agree [img]i/expressions/face-icon-small-wink.gif[/img] }}

# No Personal Chats
If you want to chat with another member of the forum, please use the PM feature, email or instant messengers. Threads which contain large amounts of posts by just 2 members will be closed.
{{ yeah .... most threads, even threads that involve back and forth between two members, typically are for the good of other people. If you've got a very specific comment for a person, you are definitely better off pm'ing them than posting in a thread (unless it is specific to that thread). Use the functions of the board }}

# Do not use more than one member account concurrently
Lately some forum members have been creating and using more than one member account to appear as more than one person on the forum. This behaviour is no longer tolerated. Use only one account over a period of time and do not frequently change accounts. If you want a different username please contact an Administrator.
{{ this pretty much applies here too. I don't think the mods are really checking for this right now, because it hasn't been a big problem from what I've seen. But generally it's pretty shameful to try to get away with breaking rules by hiding behind multiple names. }}

# Do not post inappropriate images (porno/hentai)
Do not use the image or attachment features of the forum to post images with adult content (porno/hentai), extremely gross pictures or other images not suitable for minors.
{{ ok, so this one only applies to certain threads. Not to the boobies thread, for example. If you're going to post something hardcore or offensive, or even softcore and mildly offensive, it'd be appreciated if it's in a thread that'd imply that there's going to be pr0n there. }}

# Signature Images
Putting images in your signature is allowed. However the following limitations apply:
{{ read the rules on the sigs here, of course. They differ from animesuki's enough that I didn't bother copying them }}

# All threads must serve a purpose
Useless threads will not be tolerated in any forum. The forum most frequently abused by useless threads is General Chat. The purpose of the General Chat Forum is to discuss topics not related to anime or BitTorrent. This does not mean that General Chat can be used to discuss just anything. Even here, threads must serve some purpose. Below are listed a few of the most frequent examples of purposeless threads. However, there are exceptions to this list. If you want to create a thread of one of the below types that you think may serve a useful purpose, just PM a moderator. Then if you get permission, mention whose permission in your post. Otherwise, no new threads of these types may be created without permission. Violations will be closed or deleted.

* No "forum games" allowed
These are threads like "the word game" or "the person above you", or "can you read this". These threads will be closed.
{{ ok, forum games are allowed, but only in the "general discussion area" would they be appropriate. So no "person above you" game in the naruto forums, unless you want to look like a moron afflicted with a severe case of ADD }}
* No "Rate that" threads allowed
A distant cousin of the forum game, this thread asks people to rate each other's avatars, signatures, or other aspect. There are already a few "Rate that" threads on AnimeSuki and these are the only ones that are allowed. No new ones may be created and the already existing ones might be closed (permanently or temporarily) if a moderator feels that they have strayed from their appointed purpose.
{{ honestly, when you go back a month later and look at "rate that avatar" and everyone's avatar has changed, it becomes a waste of space. If you have to, make sure you pick an appropriate place }}

* No "What type are you?" threads allowed
A thread is a "What type..." thread if it requests some sort of trivial information from the members of the forum. (Such as "What is your height?") These threads serve no purpose.
{{ generally this is the sort of thread that you probably want to avoid, or maybe post once in and then go away from and ignore forever, because they tend to be ghey. especially when there's like 800 responders. If you must, be aware that you'll probably again look like an ADD-afflicted moron }}
* No trivial polls allowed
Strongly related to the "What type..." thread, this beastie asks for people to respond to a poll with some pointless question like "What is your favorite Final Fantasy Game?" or "Are you a virgin?" Note that anime related polls are exempt from this rule, so you can feel free to create polls like "Who is your favorite girl in Maburaho?" Those polls may not be marvels of brilliance, but at least they are topical. If you can't figure out the difference, then ask a moderator.
{{ this is just a good guideline. Don't make bad polls. Don't participate in bad polls. If your poll has only 2 options, it's probably bad. }}

Most of this stuff is "be a good netizen" basics. In the relevant part though, sometimes it's difficult to figure out where a conversation becomes an exclusive conversation. If in doubt whether you should be replying or messaging, ask yourself "do the rest of the forum people want to know this" -- most of the time you'll find that if you're going off topic, they probably don't. If you have to comment about some user's posting habits, or their bathing habits, or anything else that's not somewhat on topic (or at least on a direct tangent to the topic) ... that's what the pm feature is for.

Blaargh.