When submission guidelines ask for a bio of the author to be included in the submission packet, what are editors looking for in general? I have no previous publications to list in the bio, I'm still trying to get that first publication.1. Don't be cute. At this stage, the bio is about information, not personality. (The bio that eventually goes on your book's backflap might have some touches of personality, but that's later.) So don't tell me you're a "former kid" or that while you're not an expert on a subject, you have "a lot of theories" about it.
2. Don't be weird. Discretion is the better part of valor. You're making a good first impression, so don't over-share. If you're a mother, it's ok to say you're a mom and leave it at that. If you're a mother of seventeen children (twenty-two if you count your husband's other wife's kids), then it's ok to say you're a mom and leave it at that.
3. Try not to veer off topic. I really don't care how many pets you have. Or their names. Or their recent surgeries.
4. Tell me if you are a teacher (not a homeschooler), a librarian, a bookseller, or if you work in publishing. I do not care if you are a nanny, professional clown, swim coach, or ventriloquist. I don't care if you're a fricking play structure-- it's not about how many children you come in contact with, it's about how many children's books you come in contact with.
5. Tell me if there's anything that will help you market the book-- a blog, a lot of experience giving entertaining presentations, whatever. Keep this to the things that will look good on paper-- if you happen to have a cousin with a van/loudspeaker setup, you're going to have to talk us through how driving through the city streets broadcasting "Come And Sit On My Lap and Other Stories! A Magical Trip to the Funny Spot!" is going to help, and that's a conversation for later, possibly with our lawyers.
6. If you are writing nonfiction, tell me if you're a specialist in the nonfiction topic you're writing about. Do not tell me you're in insurance if your manuscript is about caterpillars or teddybears. And if your manuscript is about insurance, well, your manuscript had better not be about insurance.
7. Tell me about your previous books published at houses that paid you for your work. If there aren't any, say "I am not previously published."
8. If you can't say anything else, tell me what inspired you to write about this subject, while strictly adhering to rules (1) and (2). Do not tell me that writing about unicorns is your "dream vision." Do not joke that the idea for your novel about mail bombs came to you after a particularly vexing experience with a publisher's submission process. Do not tell me you're writing about china dolls because you have a collection of 379 of them from around the world and they line the walls of your writing room and with them watching you, you "never have to feel alone."
As I have said before, every query, every cover letter, every submission, is really just trying to get across two big things: (1) How great your manuscript is. (2) What a yahoo you are not.
If you can get those two things across, you don't really have to worry about anything else.