Your first step in getting hired is to build your “book”, just as it is in copywriting, or in any form of paid writing. Your “book” is your portfolio. Take as many blog jobs as you can, so you have experience working with a large number of companies. Add your best posts to your book.
Let the companies with which you work know that you’re available for a blog managing role. A company may want you to work in-house, but many large blogs are run by virtual teams, so you can work from anywhere.