The most important writing tool I own: a notebook.
Bloggers by definition are writers. They may not write stories, but they write enough to fill many books. It doesn’t matter whether you blog about yourself or random and esoteric topics that only matter to you (cough: guilty). You are still a writer. If you write about yourself, you are writing an autobiography. If you write about current events, you are a journalist. If you write anything at all, you are a columnist, a historian, a science writer, or whatever title you want.