Here's the deal with Twitter:
Unless you're Ashton Kutcher and you have millions following you on twitter.
Or you're a literary agent and thousands are following you because they want you to represent them and turn them into the next Stephanie Meyer.
I think it's a nice gesture to follow someone on twitter when they've been kind enough to follow you. It's simple, too. You just open the e-mail, click on the person's name, and then click "follow."
Twitter isn't easy to get into, not by any means. But once you do you'll start to enjoy it more than you thought you would. You'll also be connected to a lot of excellent things you would have missed otherwise. And there's a lot less "noise" on twitter than on most other social media.