A quick lesson in Tennessee dialect:
The spoken word What it actually means
yawl you all
yawl you all
hail no hell no
lay-us gnat last night
wail owl rat well all right
yeeeeeeee-haw this experience is quite enjoyable (useful for
everything from eating fried pork skins to making love)
And so on. After a few days in Knoxville or Nashville, you can learn enough to understand restaurant specials and converse with the locals a bit. After that, hopefully, your drive home will be long enough to shed all the words you've recently learned and return to normal speech. If there be such a thing.
There are some two dozen distinct major English dialects recognized in the United States. Some cover a broad area, like the Southern Appalachian voice that includes Tennessee-tawk. Some are only used in restricted areas, like San Francisco Urban, New York Urban, Boston Urban, and the extra-hard-to-understand Gullah of the Charleston area. One I like, especially when used in singing, is Louisiana Cajun. Near where I live there’s a dialect peculiar to only modest-sized Harkers Island, preserving remnants of the old Elizabethan tongue (high tide to them is “hoi toide”).
Using dialect and foreign-language accents in writing dialog can be a challenge. If you try to portray a hillbilly speaking, for example, and you replace the g on all words ending in “ing” with an apostrophe, you could soon have a page swimming with tadpole-like apostrophes, only confusing and slowing readers. The late Elmore Leonard solved this by not using any apostrophes at all, simply spelling out dialect words semi-phonetically (but still recognizably).
The best advice I’ve heard is to use dialect words sparingly in the first place, then go back during the final self-editing and cull out even more of them.
In conveying dialect and foreign accents, the merest hint is almost always quite enough.