1 Research, research, research
Readers of historical fiction demand that the author accomplish the required research. How your characters talk, how they dress, what they do for a living, and the normal activities of that time, must all be accurate. In my novel War Calls, Love Cries, I refer to a rubber sheet. A dozen pages later I called it a plastic sheet. Plastic was not invented until 50 years later. Oops!
2 Be historically accurate
Historical fiction does not give you permission to change or rearrange the events of history. If you can Google it, so can your readers. Any narrative which includes well-known events or people must be accurate.
3 Use explanatory notes
It is not unusual to take small liberties with minor historical events and explain it at the back of your book in a series of footnotes. A good example would be the description of two particular events as having occurred just days apart, when in fact the second event occurred a month later. These minor changes are not usually a problem.
4 Blend your character into history
By this I mean insert your character into the major events of that day. How did your characters react to natural and man-made disasters, political events, or anything else of significance? If the characters are not genuine, it won’t matter if the events are historically correct. Your readers will be disappointed.
5 Start early
Historical fiction is a time-consuming and tedious process. Experienced writers will tell you that almost every paragraph requires at least some research. At times, it takes hours of research just to confirm or abandon a particular sentence. Pick any time period you wish. Do you know the mode of transportation, the commonly eaten foodstuffs, what a woman wore on her wedding day, a day’s wages, the average man’s height, a child’s playthings, or the cost of a rented room? All of these facts are critical to the author’s most important task, which is transporting the reader to a specific time and place.