Save a copy of your blog.
Backing up your blog is a very simple exercise if you use Blogger.
Log into the Blogger website. Go to your blogs settings page. At the bottom of the setting there is a link for other, go to this page. At the top, there is the option to import blog, export blog or delete blog.
In this instance, you want to export blog. Doing so will safe all your posts and comments to your desktop. Your content and comments will all be saved in one .xml file.
You can keep this file as a back up or you can use it to export your blog content to a new site.