There are many things to worry about as an author. A few of them are actually important, while many are probably irrelevant. For example, my two Bernie & Tish novels (almost ready for queries) are aimed at the 7-11 age bracket, generally termed "middle grade" although definitions of that vary.
For those ages, there are a few guidelines I've gleaned about what to avoid:
- No sex (overt romanticism and crushes are okay, but keep off the bases)
- No profanity (even if 11 year olds you know swear, teachers might read this aloud)
- Violence should generally be off screen (opinions vary)
- Make it exciting
- Friendship is very key to this age
- Themes of growing up and independence (different than YA independence, which is more about leaving home and going out on your own)
- Learning your power and how to use/not abuse it (not superpowers just regular powers)
- Novel length - I am aiming for 30,00 words for my novels, which may be the right length and may not be. Is that really important to kids? Is it important to agents/publishers? Not sure.
- Chapter length - I aim for 1000-1300 words in a chapter. That feels right to me, and it seems like whether a teacher were reading aloud or a kid were allowed one chapter to read before bed, consistency and predictability would help. Is that really important? Is it even the right length? I am not sure.
- Innocence - My stories are relatively innocent and straightforward. Some modern middle grade books seem to fall into either far more complex or far more violent/scary/disturbing than I like. Is that what kids want today? Is it what publishers want? Am I underestimating my audience? I am clueless, but write stories the way I enjoyed them as a kid.
- Language - I write by instinct and experience. Do I use too many big words? Too few? Out of date terms? I don't really know. I have read a lot of books for this age, so I think I am okay. The MS Word review says the Flesch-Kincaid reading level is 4.4, and while I don't put a lot of stock in that as it mostly has to do with words per sentence, etc, it is right about where it should be.