A really nice summary of all things Steemit can now be found at www.steemithelp.net. There you can find all kinds of information on how Steemit works. Everything from the signing up process, to navigating the platform, learning the basics, posting and curating, an introduction to other tools complementary to the eco-system, etc. etc, this truly is an amazing website and I encourage everyone to take a look.
It also has a quite good overview of the Steemit etiquette. And even though that etiquette is well eloquently written there, I feel that the accounts that are not conforming to this etiquette will probably never read that in the first place. So here's a summary, a little more blunt, in Game of Thrones style:
Don't post and run

Don't over-post

DON'T POST NUDITY OR GRAPHIC IMAGERY UNLESS YOU TAG IT WITH NSFW

Don't be a fake, plagiarise or pass off others' work as your own

Don't engage in tag spamming

Don't re-steem everything you see

Don't post unrelated links in the comments

Don't directly ask for votes

So what do you think? Are there important parts of Steemit etiquette still missing? Hope to hear from you in the comments!