You should bookmark this infographic about social media etiquette. It's helpful when you have questions about when to post, what to post and how to post it on all of the popular social media networks like: Facebook, Twitter, LinkedIn, Google+, Pinterest and Instagram. For example, on Facebook, it is important to engage with your fans, post entertaining content regularly and make the fans feel welcome on your page. Another great tip but for Twitter is to not use all 140 characters: statistics have shown that if you leave some space or unused characters that post (tweet) is more likely to be retweeted.
Remember that each social media channel has it's own particularities. This infographic reminds us on how to "behave" on each of them.