What are some tips for social media etiquette for businesses?

Just be natural, open, and honest.

One important thing to keep in mind is that while it is part of a greater marketing strategy, you shouldn't measure social media in the same way as other marketing methods.
Instead of hard numbers, social media success should be measured through relationships and how audiences interact with a brand.
Too often brands make the mistake of focusing on getting a large number of followers when they should be trying to develop a community that interacts with them, no matter the size.
A small active group is in reality much more successful in terms of social media marketing than a large group that doesn't interact.
Brands should also provide their followers with a variety of different kinds of content.
Unique content, such as competitions, discussions, special offers, and photos/videos, is great because it keeps people coming back to the page, however you also want to provide followers with content found elsewhere in your marketing.
People like receiving information through their favourite channels, so make sure you provide this information across a variety of platforms, including social media.
Mixing unique and duplicate content is the best way to move forward with a company social media strategy.

Businesses can ruin their entire image and reputation if they are not always very diligent about the social media activities.
It is essential for businesses to: - Always be professional - Post what is relevant to their audience - Accept feedback (good and bad) - Answer supporters' concerns - all of them - Refrain from bragging - their "supporters" already "support" them, there is no need to mention they are the best every other minute - Not be spammers: frequency of posts should be kept moderate.

Well I believe posting good content and keep it related to the products are service is advised, monitoring customer comments  and remove any disrespectful comments or postings from the page. Most of all data and identity protection of users.