I've had a lot of fun, and spent a lot of time and sweat, rendering various dialect and accents for my characters in Kindred, including Scottish, French, German, English, Irish, Quaker plain speech, early backwoods American, and the dialects of slaves of varying education and experience.
In fact, it was to do with the subject of accents that I began writing Kindred in the first place. Diana Gabaldon, author of the Outlander series, wrote a minor character into her fourth book, Drums of Autumn. That character was Josh, a slave on the North Carolina plantation River Run, owned by Jamie Fraser's aunt, Jocasta. I was as astonished as the rest of the characters in her book when Josh opened his mouth and out came a dialect of Scots.
What in the world? Well, of course it's explained in context. If Josh grew up owned by a Scottish family, and was exposed primarily to that way of speaking, it follows that's how he would speak. But I was still curious. Had Diana based Josh on someone she found in her research, or was he a fabrication of her fertile imagination? Fortunately, since I've hung out at the Books and Writers Community off and on for about a decade, I could ask her (Diana is on staff there). When she told me she had run across several instances of slaves, owned by Scottish families, speaking both Gaelic and Scots, I began to wonder what that situation might have been like from the point of view of the slave... or perhaps the child of such a slave. Mother and daughter, say... and so Lily and Seona came into being.
Back to the task of rendering such dialects and accents in written dialogue. I've been told that less is more, and to strive for a cadence of speech unique to the nationality of the speaker, rather than employ excessive phonetic spellings (or misspellings) of words. The latter can be hard to decipher and tends to create a visual stumbling block, while the former gives the flavor of accented speech, while remaining easily readable. Choice of words and phrases, a sprinkling of idioms, a few foreign words or phrases now and then, help to render a character's speech into a recognizable and believable accent or dialect.
Picking up an ear for accents has been a long, organic process. From reading primary sources like letters from the period, and journals, to novels written at the time (I just finished listening to Robinson Crusoe, published in 1719, and which my literate characters would likely have read). I also read as many modern historicals as I can get my hands on, in which the author has done a skillful job in rendering whatever accent I'm currently struggling to bring to life on the page.
It's also great to belong to an international writers forum where I can vet my German, French and Scottish accented dialogue with obliging folk who live in those countries or speak those languages fluently--or know those who do--and will correct my errors without laughing their heads off at me (at least not to my cyber face *s*).
And just for fun, Project Gutenburg has a dictionary of Scottish proverbs you can read on line, or download for free. The Proverbs of Scotland, by Alexander Hislop.
"A bark frae a teethless dog is as gude as a bite."
This post is getting long. I'd meant to add a few more snips of dialect from Kindred, but I'll be after saving them for future posts.