If slush is a journey, most people are packing way too much luggage.
I can't tell you how often I have to throw away 5-10 sheets of the submission before coming to the manuscript. Here are some things that you really don't need to include:
1. An author photo.
Why do I care what you look like? Everyone knows that there are some very pretty, friendly-looking people who haven't a talented bone in their bodies but who will keep submitting manuscripts, appearing on reality shows, saying things in public, and otherwise making themselves a flagrant aggravation. They give new meaning to the term "attractive nuisance."
2. All the little flourishes.
The letterhead with the plume-and-inkwell motif (god, if I never see another one of those, it'll be too soon); the stickers; the colored envelopes; the random enclosures that I'm sure you thought were a kind gesture or had something to do with your manuscript. (I don't take candied walnuts from strangers. Or fruit. Or puppets.)
Want to make your submission look professional? Make it look plain. Professionals, remember, are people who have sent out many, many copies of many, many manuscripts and who have realized that when you're dealing in that kind of bulk, all the extras are a waste of time and money.
I try to look past the foofaraw, but trust me--some editors are judging you.
3. An author bio
The only thing I want to know about you at the outset is your publishing history, if you have one.
I do not care if you teach preschool or have seven grandchildren or get along great with the kids across the street. Being good with children does not make you a talented storyteller. I only want to know if you're a good writer, and your manuscript is going to tell me that. Besides, some of the very best writers for children have hated children. They respected children, but they didn't want to spend any time around them.
4. Market analysis
I've seen these included several times, and I still can't imagine what's included in them. Because I've never read one. Never. What in god's name makes you think you know more about the market than the people at publishing companies, who spend an extraordinary amount of time charting the market?
5. Publicity plans
This might or might not go over well with a publicist; I've never asked one. But your submission is being read by editors, who are happy to let publicists do their job and really don't care whether you think your cousin's hairdresser's niece can give your manuscript to Oprah.
6. Overview and synopsis
I don't know how anyone manages to have both. And are editors asking for chapter-by-chapter summaries? I only backtrack to a synopsis if the writing's really good and I'm wondering if the author knows where the story is going.
7. Competitive research
It always lightens my day to open a fantasy submission that has a page of competitive research that includes, in its entirety, Half Magic, Harry Potter, and Eragon. If you think that's your competition, I think I'm going to double over laughing so fast I bonk my head on my desk.
Competitive research is something you should do for your information, but don't send it to me. I'm better at research than just about every author I know, and being fully informed about a project I take to acquisitions is part of my job--and not a part that I'm going to trust to you. If I like your project, I'll do the research.
The moral of today's blog:
Why check baggage that no one is going to claim?
Cover letter and manuscript. And SASE, if requested. That's it. Really.