Define what your blog stands for
Brand is what people think of when they think of you. Before you touch visual identity, decide your editorial stance: what topics you cover, what you will not cover, what perspective you consistently bring, and who you are writing for.
What topics will you cover? Be specific. A blog about "marketing" is not a brand. A blog about "email marketing for independent retailers" is a brand. The more clearly you define your territory, the more recognisable you become within it.
What will you not cover? Deciding what is out of scope is as important as deciding what is in scope. Readers trust blogs that stay in their lane. A blog that covers everything has no point of view.
Who are you writing for? Picture one specific reader — their job, their problem, their level of knowledge. Every post you write should serve that reader. A blog with a clear point of view is easier to brand than a blog that covers everything.