A quick lesson in Tennessee dialect:
The spoken word What it actually means
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 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.