I've gotten a bunch of questions recently about etiquette on Twitter. There really are no formal rules, because lots of people use Twitter differently. I know lots of people who have rules that are different from me, and that is fine. Their personal style may be different or maybe they use Twitter "better". You can use twitter however you want (and don't let one of those "social media experts" tell you differently).
While I do not think there are any formally established etiquette for Twittter, I thought I would share how I use it. Let everyone know in the comments if you agree, disagree or have other ideas for what twitter etiquette should be.
My etiquette for reading tweets - You cannot and should not read all tweets. There is just too much volume on Twitter. Twitter is not your email. I snack on Twitter a couple times a day for 10-15 minutes at a time. I read all of the @mvolpe messages and I try to read all my direct messages (DMs). I do not have any messages or DMs sent as text messages because I don't like to let Twitter interrupt my day.
My etiquette for following other people - I follow people that say something interesting to me, seem to have a high value to tweet volume ratio, talk about me or my content or retweet me, or people I have met in person. None of these rules are set in stone, but the more of these things that apply to you, the more likely it is that I will follow you. If you feel like you are left out, just ask me by sending a message like "hey @mvolpe - I love your tweets! Would you mind following me back?"
My etiquette for following people back - I do not automatically follow people back because the follow me. I used to, and I found that I got even more DM spam than I do now, and a lot of the following was coming from robots, so I stopped. I figure that if you followed me and I should follow you back, one of the conditions above will eventually apply to you and you'll get followed that way.
My etiquette for direct messages (DMs) - People who have a lot of followers and follow a lot of people (more than 2,000 of each) get a lot of direct message spam - do not assume they receive or read all of your DMs. I can't and don't. I do my best to read them all, but honestly many good messages get buried in there. Sorry.
My etiquette for retweeting - If I know you well (in person or virtually) and you ask me to retweet something, if it is good I probably will do it. If you say something remarkable, I might retweet it without you asking.