I joined Twitter recently and I'm gradually getting into it. I'm just tweeting randomly, mostly about news, media, politics and entertainment. It's not an SEO, blogging or marketing related Twitter page - although I might start one of those in time.
Anyway, the first thing you want to do upon joining is get more followers. Many just start following as many other "tweeple" as possible, knowing that a certain proportion of them will follow them back. But I think this is a bad strategy. It's kind of like traffic exchanges. The only reason people look at your site is so that you will look at theirs!
In the long run it's best to find people to follow who have a genuine interest in what you're tweeting about. Then you'll enjoy their updates, and there's a better chance that they'll follow you back. That takes a bit of time, of course.
One good way to do this is to search for some specific keywords and see what comes up. So it's kind of like Googling, except in real time (the tweets get indexed instantly).
If you are into something that tends to be quite polarized, like politics, then you'll want to find people who see the world as you see it. That's a bit trickier, since keyword searches might reveal people who are tweeting about what you are passionate about, but they might not have any particular interest in it.
Say you're a climate change activist, and you want to find others to network with. You search for those two keywords in the tweets. There will be an ocean of results, since it's such a big issue now. But most of them will be from people who have no specific interest in the subject. They are just posting about it because it keeps coming up in the media. They might be worried about it, but feel they are powerless to do anything to stop it. Or maybe they don't believe it's real at all and couldn't care less! Clearly, following them would be a waste of time in the long run.
So here's a better strategy: If you type in the name of a columnist, public figure or even media outlet renowned for espousing a particular view related to your political passion you'll find a lot of twits who are very clearly for or against. (In the case of climate change these might be search terms like "Al Gore", "Christopher Monckton" or "Fox News".)
You'll still have to wade through the tweets to find those on your side. But it's pretty quick because they will generally be passionate and therefore unequivocal.