Sometimes it seems like twitter is nothing more than a place where people relay headlines with links to magazine articles and newspaper stories. Yes, I understand people can't hold themselves back from sharing information, but the s*** hits the fan for me when some idiot tweets out last week or last month's news as if it were fresh. I just want to reply "we know that already, dumb ass, it was the buzz on twitter two weeks ago."
But I'm just as guilty as the next twitterer. I will send out RTs and MTs sometimes like there's no tomorrow. But I have found that original material, when tweeted, is far more effective and goes a lot farther than "tweet this" links form blogs and online publications.
At the very least the creative constraint associated with getting your message out in 140 characters or less is a good thing. And twitter totally blows RSS feeds out of the water when it comes to alerting the public to a new blog post or online article.
Kim Komando typed up one of the better articles regarding the effective use of twitter. Read it here.
If you notice certain people trying to "make money" on twitter, un-follow them. They waste time. Especially the ones who for some reason tweet the exact same "opportunity" 5 or 6 times in a row. (I'm not sure how that happens, as twitter won't allow users to tweet the same thing a second time, but these marketing guru-idiots have apparently found a way around that.) So un-follow them, ban them, whatever it takes.
Whenever possible, tweet out fun, original stuff - text, pictures, links that can't be found anywhere else. Think of your followers as "good friends" with whom you'll share a slice of your personal life from time to time. I'm not sure how many tweets-per-day I read, but it's a good amount. And I limit those I follow to 300 or so. It's a good number - about 30 of those twitterers are extremely active on the microblogging platform - and roughly 100 tweet once in awhile. Every few months I go though the list of those I follow and un-follow any that haven't tweeted in a long time (months or more). Sometimes I wonder what happened to someone who once was very active but went silent. So if you get tired of tweeting, you should still send out a few a week to let folks know you haven't abandoned the platform.