Oh, hello. Welcome to Jeffrey’s Internet Etiquette Soapbox, where I passive-aggressively explain to you how obnoxious you are based on the trivial actions you take on a trivial social network!

Retweeting when someone replies to you with a compliment
The cardinal sin. There is no reason anyone would be at all interested in what some random person thinks of you. Your mom stopped caring when you turned five.
Retweeting when someone includes you in a jumble of usernames with the “#ff” hashtag
Congratulations! Someone thinks you’re worthy enough to be part of the cast of characters in their Final Fantasy fanfiction. Your followers already follow you. When they see that you’re included in a list of people to follow, they second-guess whether they should have followed you in the first place. Do you want that?
Retweeting when someone replies to something that you say
Unless what the person says is funny or interesting in its own right, there’s no need to retweet them for all your followers to see. Not even when they’re answering a question. We don’t want to be invited on a quest to discover the answer, since no one cares but you. If anyone did care, they’d check the replies to your question themselves.
Putting pound signs before words, or concatenating words prefaced by a pound sign
Pound signs serve no purpose; remove the key from your keyboard. I don’t care that it’s also the key for “3”.
Telling people where you are
No one has to know that you’ve left your basement. Take it to Google Latitude, where no one will hear about it. Have you ever bragged about patronizing McDonalds before the advent of Twitter? There’s no reason to start doing so now.
Posting nothing but how relaxing of a day you’re having
One can only surmise that you are only relaxed when you’re tweeting something pleasant, and at all other times you’re a nervous wreck.

In summary, if you ever stop to think about whether what you’re about to post has any relevance or use to anyone besides yourself, the answer is probably “no”, so put your phone away and pay attention to the tree you’re about to walk into.