Just starting out?
I think it is a good practice to start your blog as private while you test things, experiment, and grapple with the subject matter of your blog.
You will feel freer to try new things and make changes, both to content and design, if you know you are the only reader.
Once you've gotten into your subject, are happy with the design, and have a few posts under your belt,
then take your blog public. The setting is at Settings > Permissions > Reader Access ? private to authors.
Meanwhile, you may find that your blogging takes you to an unexpected place. As related
elsewhere, the focus of this blog got taken over by by my first-post-first blogger hack, which was really just a rough idea at the time.
Consequently I changed the name to "Too Clever by Half" and matching web address, and made a few design changes.
It was the
practice of blogging—of learning and thinking and writing about my subject matter—that led me to this new place. Planning only gets you so far.
I could have made these changes after going public, but that would have been more work, more awkward, and potentially confusing to readers.
Because I started in private, I was able to make these changes quickly and easily.