#9- Don't respond to @ mentions. Even if you ask a question of the twitterverse, and people respond to your question, do not respond to them. It makes them think that you "value" them.
#8- Use Friday as the day to @mention as many people as possible. #FF is just a way to say "Hey, you're following me. Here's a link." In order for this to really work, you need to mention at least ten people in every tweet, and tweet a new list every thirty seconds or so. This way you can reach maximum spam effect.
#7- Be passive aggressive. Twitter is the new Facebook. It got "annoying" to put your business out there on Facebook, so do it on Twitter instead. This is particularly awesome because most passive-aggressive rants require far more than 140 characters, so you'll have to break it up into multiple tweets. But since you will write it in order, and everyone's timeline shows the most recent tweets first, they will read everything in reverse order, starting with the last thing you said! (thanks a lot, @KimbaMcG)
#6- Be a bot. (on a completely serious note, does anybody understand how bots have followers? or is this a mystery only confounding me and @sweeneysays?)
#5- Type lik dis 2 sav space. U no its NBD. U R 2 Cool 2 wrry bout vwls n stuf.
#4- Use TruTwit Validation Services. Hi, there, person I don't know. I want to confirm you are not a bot, so I will use a bot to confirm this. Please enter in a code so that you can be deemed worthy of reading my passive-aggressive and/or self-promoting tweets.
#3- Use an automated Direct Message Service. This way, everyone who follows you will get a beautiful, generic message thanking them for following (they are really doing you a great service!) and wishing them a great day. It is a touching way to show all 313,596 followers that you really care. BONUS: Use automated DMs to tweet out self-promotional links to new followers as soon as they sign up.
#2- Beg for attention. "Plz like my FB page" and "Plz RT"* and "Plz comment on my blog" tweets are totally legit. Nobody gets annoyed. It's not spammy. And it's completely different from the self-promotional stuff.
*I want to put in a note on the "Please Re-Tweet"/"Plz RT" notes: there are times you are genuinely trying to either a) disseminate important information or b) get an answer to a question and re-tweets will help you accomplish your goal. When this is done NOT in conjunction with self-promotions and other behaviors on this list, it is NOT alienating at all. So... do it only if you want people to like you. Like that matters.
And, the #1 way to alienate people on twitter is...
You tell me. What are the most annoying things that people do on Twitter?