Historical fiction. It has to be my favorite genre! Not only do I enjoy reading it, I also enjoy writing it. And as I have read and written it, there have been a lot of things that I've noticed. Sometimes it is simple things that will make or break your story.
1800 - You have this kid who says cool.
Actually, it wouldn't be a kid at all -- it would be a child. And "cool" is totally out of his century.
1750 - All of the families have 2-3 children.
Depending on the culture, some of the families would have had 2-3 children, but that was probably due to deaths of children (during childbirth, as infants). Otherwise, if you're speaking English culture, families would have had larger families.
1550 - "I'm just kidding."
What? Your character is having a baby goat? Nay. He would be in jest.
980 - "This is my dad."
The first known use of "dad" is 15th century (how do I know that? Simple online search). He would most likely be "Father."
How does your character dress? How do they speak? How do they interact with others? What do they call their grandparents, parents, aunts, and uncles? How do they spend their days? What is their occupation? The answers to all of these questions help set the tone of your historical fiction novel.
What is the terrain? What do the houses look like? Are the streets crowded and dirty or clean and free of clutter? The more you describe, the more the reader "feels at home" in your story.
What did they eat? Did they have crackers then? Soup? Bread bowls? Salads? Dressing? You could omit these details, or you could do a little research and make your story authentic.
She looked around the parlor.
What did she see? Were there couches (or were they called sofas or settees)? Did the windows have curtains or drapes? What were the colors? The ambience? Going from the parlor, what is in the kitchen? A butter churn? What about the barn? Are the walls lined with tack?
Things to Remember
Don't assume. Do not assume that a published fictional book is accurate. It might be a good place to start with research, but don't use it as the encyclopedia.
Research pays off. But be sure that you're researching in the right places. The internet has great sources and the library has great books, but anyone today can have a website or publish a book. Check your information -- if you find 2-3 places that say the same thing, chances are you're pretty accurate. And remember: the best place to find solid information is in original documents, newspapers, etc.
Read books that were published in your era. If you're writing in the 19th century, you have a world of books you can obtain that were written in the 19th century! And who would better know their century than those authors?
Writing historical fiction is the best tool to learning history -- and you will unearth some pretty amazing treasures as you research! Don't let the magnitude of work discourage you from writing. Learn as you go, and be willing to test your historical authenticity.
What makes a historical fiction novel authentic to you?
What hints do you have for writing historical fiction?