Your historical fiction depends upon your ability to use historical detail. This is a different world for your reader. You have to supply the images and they have to be the right ones for this world.
What is the street like? Does it smell of horse shit? Of smog from the factories and chimneys? What kind of wagons or other conveyances are there? What is the noise? Street vendors crying their wares? Horses? The clatter of armor or harness? Plate armor? Maille? What did the clothes look like? What was the lighting?
Don't recycle information from old, and often totally inaccurate, movies and novels.
If you are going to write about people living in 1200 England, you need to know how people lived there. How is that woman in the home you're writing about making yarn for clothes? She did make her own. Don't assume she used a spinning wheel. They weren't used yet. So how did she do it?
What kind of horses did people ride? Knights didn't ride a destrier down the street, by the way. That would be very much like driving a Sherman tank to the grocery store for a gallon of milk. What was a palfrey? A courser? When were the different horses used? How were they different? You're writing about a sailor in the early twentieth century. What was life like on a British merchant ship? What did they eat? What were the uniforms? Could a sailor work his way up to become a ship's officer? If so, how?
It's easier to track down someone who knows about a distaff and spindle or medieval horses or how one worked their way up from below the deck than it is to track the answer to every question on the internet, especially since the internet is often inaccurate.
Google for non-fiction books on topics you want to learn about. Wikipedia is often a good source of lists of non-fiction books used as sources--a much more useful way to use it than assuming its articles are accurate. Compare comments about different authors to see which seem to be widely considered accurate. Often an email or a call to these authors will yield a world of information. Of course, calls to museums can also be a possibility, but often finding someone there who is an expert on what you need information about is not that easy.
For one novel, I needed to know how long it would take to spin enough yarn to weave cloth to actually make clothing in a 12th century household. This took some tracking down. A forum for hobbyists yielded a list of books. A call to an author eventually gave me the information I needed.
It is the small stuff that gives your novel the feel of authenticity. You have to know a hundred times more about the world you write about than goes in the novel. Believe me, if you don't, the reader can tell.