Step #1 is understanding what it is. An author’s bio is a marketing tool. It is a way to convince someone who is already reading your work to read more. See, no pressure?
Once you understand that, here three tips to get you started.
Consider the piece it accompanies. When my bio accompanies educational writing, I talk about my work in educational writing. For my book, The Ancient Maya, I wrote about my background in anthropology. For Black Lives Matter, I talked about living next to Ferguson. Whether your bio accompanies an essay in an anthology or an educational book, you need to customize is for this particular piece. Come up with other publications or something in your background that pairs well with this piece of writing. If this is an online piece, I make sure that I include a link to something else.
This isn’t just a reading list. When you write your bio, give them more than just a list of your other sales. Yes, you want them to read your work but you also need to include other information about you. I’ve seen writers include information on their families, their pets and where they live. Hobbies, other jobs and favorite foods are also fair game depending on what piece of work the bio accompanies.
Include something quirky. Especially if this bio accompanies a piece of writing for children or teens, include something quirky or fun. For a book on horses, I might tell them that I once wrote a piece on horse poop. For the Maya book, I could include working on archaeological dig as a teenager. Writing a book about careers? Include some of your more interesting professions. When one writer I know sells a piece of horror, he includes the fact that he was a gravedigger.
Write it in the third person. In my case, I always start “Sue Bradford Edwards lives/writes/is …” It takes a little getting used to but at this point I actually find it easier to write my bio in third person. It sounds less braggy.
It might talk more than one try to get it right but once you have some idea what to include there is no reason to let your bio intimidate you.