I’ve collected a lot of resources over the years and have been trying to clear them out (I have a long way still to go), separating the ones I’ve actually used from the ones I’ve never thought of again, or ones I once thought were good but have outgrown. Some of them I thought I’d share. This particular collection is online articles on historical fiction I’ve found useful or interesting.
https://historicalnovelsociety.org/guides/defining-the-genre-what-are-the-rules-for-historical-fiction/ (a transcript of a speech by Sarah Johnson of Eastern Illinois University) has this thought-provoking line: “Some readers go so far as to say that a novel should only be called “historical” if the plot reflects its historical period so well that the story could not have occurred at any other time in history.” That is truly a high standard to reach for, but as both writer and reader, I think, not a bad one. In the Christian view of history as itself one long story, with each moment unrepeatable, stories which show events in past times and places as all being vaguely same-ish are doing a very poor job indeed. At least, I’m assuming the stories all have some concern with the human condition and the uniqueness of particular characters. (The Historical Novel Society has a very helpful website in general; and see also: https://historicalnovelsociety.org/guides/how-to-find-a-literary-agent-for-historical-fiction/.)
https://www.telegraph.co.uk/culture/books/bookreviews/7685510/David-Mitchell-on-Historical-Fiction.html — more specifically, on what draw people to write it, with a glance at the history of the genre and the pitfalls of showing off research.
http://www.elizabethcrookbooks.com/articles/historical_fiction.htm has some Rules for the genre, if you’re the kind who likes rules for things, some of which apply to other genres as well, and some of which are quite well-taken. At a slightly more “beginner” or overview level than some of these others.
On a similar note, an authour did two posts of tips for aspiring hist. fic. authours: https://www.stephaniedray.com/2014/02/13/10-tips-for-aspiring-historical-fiction-authors/ and https://www.stephaniedray.com/2015/09/19/10-more-tips-for-historical-fiction-authors/, and a post contrasting traditional with independent publishing and the particular things to take into account for books in a not very popular genre: https://www.stephaniedray.com/2016/01/04/publishers-you-should-consider-for-your-historical-fiction-novel/.
http://www.historicalnovels.info/Writing-Historical-Fiction.html goes into depth in all of these things. It’s an interesting site in general, with lots of rabbit-holes to fall down, what with all the lists of novels separated by century and so on. . .
These two posts by Lucille Turner (on Research and Theme) are very good: https://awriterofhistory.com/2017/03/15/research-in-historical-fiction-by-lucille-turner/ and https://awriterofhistory.com/2017/03/15/research-in-historical-fiction-by-lucille-turner/. Also from the same site are two interesting ideas of what makes successful historical fiction: https://awriterofhistory.com/2017/05/18/successful-historical-fiction-with-margaret-mcgoverne/ and https://awriterofhistory.com/2017/04/04/davide-mana-on-successful-historical-fiction/.
A post I wholeheartedly agree with on common misguided assumptions of the beginning writer (or uneducated reader) of historical fiction: https://clearwaterpress.com/oneyearnovel/blog/secret-historical-fiction-wont-make-historians-cry/. “A third problem becomes evident from reading early chapters of some historical fiction, where opening scenes can go something like this: There are carriages. And a market. Some people have fancy clothes, but I am a lowly thief. We are living in approximately the year 1000–1850.”
Octavia Randolph, who has written several novels set during the Anglo-Saxon era (though as I haven’t read any I can’t vouch for them), has a good post here on the importance of historical fiction: https://octavia.net/importance-historical-novels/.
For those of you with access to Jstor, the article “Opportunities in Historical Fiction”, by Michael Williams, is worth reading although old (pub. 1922).
The Penslayer, as always, has wise words: http://www.thepenslayer.com/2013/02/it-was-not-history-then.html.
A reader of the genre complains about things she hates (which, oddly enough, line up very well with my own pet peeves) and pleads for more of the things she does like in the genre, which writers might do well to keep in mind: http://regencydelight-janeaustenetc.blogspot.com/2014/08/help-historical-fiction-genre-is.html. And some people have recommended things in the comments, if you’re looking for books to check out yourselves. Though I can’t be answerable for the consequences.
Of course, at some point you have to stop reading about how to do things and go do them.