What Mel said
Here's the short version:
(1) If you have a password protected blog or post, send out a mass email (including your password) to all the people you want to read your blog.
(2) If you have a blogger blog (meaning the url is something like myblogDOTblogspotDOTcom), click on your profile and make sure it's linked to your blog and your email. Set up a new email exclusively for blog stuff, if you'd like. Note: even if you don't have a real blog, you can set up a "blog" (just don't add any content), so you have a profile with an email.
So often, there are comments I want to respond to personally or that make me want to learn more of the commenter's story, but I can't because I can't find blog link or a profile or an email address anywhere. And that makes me all sad and frowny-faced. Which, believe me, is not exactly fetching.