Please don't submit your work if you're under the age of legal consent (18 in the UK). There are legal implications in publishing books when you're too young to sign contracts which I don't want to get entangled by. Apart from that, your work is unlikely to be good enough to impress me, and I don't want to break any young hearts.
Don't submit pornography: I can't be bothered with it, and don't want it in my house. Erotica, however, is welcome.
Books which contain gratuitous violence or overdone sex are unlikely to do well.
Don't submit any overtly religious writing, as I don't believe in gods of any kind and my remarks are likely to offend you.
Don't ask me to consider e-books, no matter how good they are. I like reading real, physical books and don't have an e-reader, and I'm not going to sit at my computer for an extra hour just to read your books.
Apart from that I'll read pretty much anything. Fiction, non-fiction, poetry, memoir; books for adults, books for children, and all ages in between; hardback, softback, illustrated or not. Send it to me, what ever you've got.