When writing historical fiction the prospect of doing adequate research seems like a given. Of course you have to research the time period and the historical events that surround or contribute to your plot and/or setting. That said, there are little details writers often overlook and these details are just as vital for creating atmosphere as the historical events themselves.
One such detail that is often overlooked is fashion.
Of course there is the generic 16-18th century costuming that we can all identify in period movies, but historical fashion is much more complex than a corset and a good coat. Just as with modern fashion, each decade had a unique spin as did each culture and country. French fashion of the 1890's was not the same as English fashion of the same decade. Similarly, fashion between 1700 and 1790 wasn't the same coat and shoe pairing for a ninety-year span. Finding these details and incorporating them into your narrative is important for setting a scene, an atmosphere, and creating a historically accurate narrative your readers will appreciate and enjoy.
Fashion 1759 and fashion 1763. Notice the bows and ruffles have been de-emphasized.
It may seem silly and you might think that your readers won't notice such a nuance but historical readers absolutely will because they love one thing: history. That means your readers read up on history and they will notice if you use a 17th century long waist coat in the 1770's when men's waistcoats had been shortened from knee-length to the hip.
1760 men's waistcoat compared to 1795. I like to call this the "why hello there" pose many men were painted in for some reason.
It may seem silly because it's just clothing and the real story is the characters and the plot so why should it matter? But it totally does. Throughout history, all the way from Ancient Egypt to modern era, how have humans displayed their status, power, worth, and identity? Through clothing and fashion. What your characters wear is as much a part of who they are as is the actions they make. Not taking the time to research the historical fashion and construction of the time is doing your characters and readers a disservice.
As a writer, you want to use as many "showing" tools as you can to improve the quality of your narrative. Fashion and clothing choices are an excellent "showing" tool for writers—especially historical writers. Want to show that your character has wealth and status? Bright colors and the high fashion of aristocrats. Want to show that they are royalty? Purple and silk of course! Want to show that they are poor, working class people? Linen fabrics and lots of browns because stuff got dirty and you couldn't just go to the laundromat.
1795 commoner clothing compared to 1785 Spanish aristocrat and 1738 Polish aristocrat.
It's these subtle details that help define and establish your character and their place in this historical fiction world you're creating. You don't have to say your character is a poor, dirty farmer—their clothes and actions can.
"She lifted up her layered skirts to step around the pile of dung the stable hand had yet to pick up, her hem caked in dry mud and the patch she had sewed near her pocket straining to hold its stitches."
When conducting your research, don't ignore the significance that fashion plays in society and the way we interact with each other. Just as it plays a role in our lives now, it has been for centuries.