“When I do Appalachian dialect or any other dialect that’s not standard American speech, it’s very important to understate it and not to use phonetic misspellings, not to drop the “g” and use an apostrophe… Let the sense of dialect...come from the word choice and the rhythm of the speech…” -- Lee Smith in When craft & storytelling come together, The Writer, April 2009 issue.Later, she says “… if the reader has to stop and read it like it’s another language, then you lose the reader.”
I've had mixed success writing dialect. I like the idea of using word choice and rhythm, instead of misspellings. I wrote a story in which one character spoke normally and the other dropped the “g” at the ends of words. This confused one critiquer. He felt the writing was inconsistent. I understood his point. I didn't change how I wrote the dialect in that story, but didn't use the format again.
I can't think of many authors who do dialect well. Mark Twain and Elmore Leonard come to mind, although I find some of Mr. Leonard's dialog tedious to read. Robert B. Parker does a good job with his character Hawk in the Spencer novels.
Someone – I can't remember who – suggested a writer use dialect for one or two sentences and then write normal dialog. Doing this sets up the pattern for the reader to continue, if he desires. As for me, except for one recurring character, I'll stay away from writing dialect and give the reader other clues as to how a character talks. For example, I assume if the reader knows the character speaks with a German accent, that's enough for the reader to hear how the person talks.