Spelling & grammar
Do make sure to point out any errors in in people's Tweets. Everybody should be as perfect as you, and make sure that every Tweet is proof red. Other Tweeters will certainly thank you for pointing out there short-comings.
Manual RT & MT
When you particularly like a Tweet, make sure to copy it and send it out as your own. The person that wrote the original Tweet will undoubtedly be delighted to be mentioned in one of your Tweets.
Originality
If somebody Tweets something similar to something you've seen before, do make sure to point this out to them. Please remember to call them a thief since, as we all know, it's impossible for any two people to have a similar thought independently of each other. That said, don't nick other people's Tweets and pass them off as your own.
#conference & your favourite accounts
If you're at a conference or similar event, make sure to RT absolutely everything with the hashtag. It won't fill up our timelines at all, and we would have no way of finding out what was going on without you. Likewise, if there's an account you especially like, make sure to RT everything they say. The best way to do this is to wait until they're had around 20 Tweets, and then RT them all in the space on 30 seconds. It is a proven fact that most people on Twitter cannot make their own judgments about who to follow based on a sample of RTs.
Unfollowing
If you follow somebody and decide that they're not your cup of tea, made sure to tell them that you're unfollowing them. Make sure to include the reason - normally just in one or two words such as 'lame' or 'not funny'.
If you do tell somebody why you're unfollowing them and the respond, do make sure to report them to Twitter and to the police.
Twitter Premium
Consider joining this ...
Image from the creative geniuses of @davidschneider, @Pandamoanimum, and @davidlberesford