For years, I worked in the legal field, so when I went to work as a pastor's secretary, and he asked me to draft a letter, you can imagine the letters would need a different "tone." On occasion, the pastor would return a letter and ask me to soften it. Why? Because a letter drafted from a law office would be much more businesslike than a letter from a person's pastor.
About right now, you’re asking what the above has to do with self-editing a manuscript. My answer: tone. Several factors can determine the tone of your work:
Genre: In a thriller, the tone has to be quick, decisive, always building conflict until the moment when the hero saves what he’s out to save. The tone matches the hero’s efforts. On the other hand, historical romances are going to be slower. The dialogue is often relaxed (though there could be deep subtext going on). Much more detail will be given to description. Characters in historical novels most likely lived in a simpler time. The tone of the novel should reflect that lifestyle.
Pacing: Very much a part of the tone is pacing, and it can be used to create conflict or to give the reader a release. In romantic suspense novels, the pace may at times be slow (but never too slow), especially as the author builds the conflict into the story. As the hero or heroine finds himself or herself fighting a known or unknown enemy or situation, the action will definitely pick up. In a mystery, the pacing is often slow. The author builds the case around the detective, introducing the mystery to be solved and dropping clues. Again, however, there will be scenes where the action should be quick and decisive, but with both these genres, great care should be given to draw out the suspense.
Character: Young adult novels are, of course, written primarily for teenagers and young adults. You will find the characters in this genre must connect with someone of that age. And surprisingly, the ones that connect the best with a younger generation will also resonate with the older reader. Character is important in young adult novels. Even issue-oriented fiction for this age range is stronger when the characters are witty—whether they know it or not—and true to that age group. Jump to the other end of the spectrum: women’s fiction has a specific audience—women between the ages of twenty and one-hundred. These are often serious, issue-oriented fiction. Again, witty characters are great for women’s fiction. Those characters provide levity to the plot, but the humor isn’t going to be the same. Have a thirty-something woman act like a teenager, and the author will lose her reader in the genre of women's fiction.
Tone is the balance of pacing and character within the genre of your choice. This is not to say that an historical romance cannot have humor or that a thriller can’t have romance. However, an author should be very careful that the tone of their story stay true to the genre.