Twitter is definitely helpful in letting others get to know you and getting them to visit your blog. As far as what to do I think that is really just dependent upon what your goals for your blog are.. it changes what you do and don't blog about when you're trying to focus on a specific group of readers. I've never asked another blogger to place my links. However it does help to have an easy to grab blog button on your blog as well as RSS subscription buttons and a technorati button as well. I think the readers just come with time and can also depend upon how much work you put into your blog. Blogging is just very time consuming but you're on the right path by asking these questions to begin with :)
I haven't found that my tweeters are very responsive... I've emailed comments back to numerous followers - with nothing blog related and no one seems to comment back.
I've kind of tried to make sure my posts are a balance of social and have posted an occasional link to a post of my own.
I feel like there is great opportunity there, but I think I'm missing something.... at the moment it's like that time is going into a vacuum.
My facebook friends have been better, but they are my real life f2f friends... so I'm sure that helps.
My blog started off mainly with just friends and family reading it but as I ventured more into social networking, I started gaining readers other than just friends and family. If you have facebook, you can add a link to your blog on there...if you're comfortable with it, you can add a link to your blog in the signature of your e-mail, if you belong to message boards, put a link to your blog in your siggie. Those are some different things I've done and have gained many readers that way.
The only time I ask people to add my blog to their blogroll is when I host a contest/giveaway, as a way for the person to have an extra entry. But for the most part if I notice I'm on someone's blogroll, I always add them to mine. And there have been some blogs that I've really enjoyed and I've sent those bloggers private e-mails asking if I could add their blog to my blogroll, and usually they are more than happy to return the favor, though I don't ask them to.
You'll see, once you get out there more in the blogging community and networking, you'll draw in a lot of readers that way. :-)
For me it is is being consistent with your posting schedule and having great content! Once you have done that your readers will naturally grow as you put yourself out there in forums such as here, Facebook, and Twitter. Mine started with friends and then just grew. I also try to write blog post titles that would grab attention in a search engine.
I have never requested to exchange links. My own links page is in dire need of an update.