Writing a novel (or anything, for that matter) is quite a lot of work. There are quite a few “rules” and “styles” of English that ultimately become the choice of the author/editor/publishing house, with the key to “correctness” being consistency. Whether you choose to employ a serial comma is up to you, but do it consistently throughout. Whether you choose to put a character’s thoughts in italics, single quotations, or leave them to be inferred by the reader, do it consistently.
But what about things like names of people and places? Especially if you’ve made them up? I’ve worked on several projects where a person or place’s name has changed throughout. Here’s my solution. Choose which one is “correct.” Do a search and find for any other alternatives that might have turned up. Make sure they are consistent.
You may also want to do the same for commonly misspelled/misused words and words that you know you have a tendency to overuse.
Remember, an editor should catch these things, but the cleaner the manuscript you send to an editor, the more they can focus on catching the bigger problems (check out #4 on this list from Katie McCoach, and read the rest of it, too).
Have you ever found an inconsistency such as these in your own works? How did you go about correcting it?