On my recent dialect recording trip to Nashville, I got to visit the home of President (and General) Andrew Jackson. Appropriately enough, a number of the folks giving the tours had variations in Southern accents, including quite a bit of R dropping, which is commonly associated with the Southern plantation sound.
Here's a brief introduction to the classic Soft-R Southern accent:
I go into a couple of the major mistakes that people commonly make with this accent:
People assume that this Dropped R classic Southern accent is THE way that Southerners talk. Julia Roberts does it pretty regularly with almost every Southerner she portrays, even when they're from Texas - and the real-life person doesn't drop her R's! What up with that?!
Julia Roberts:
And the actual Joanne Herring:
This Soft-R Southern is not the way Southerners talk... it's A Southern accent, but it is far from THE Southern accent.
This American Southern Soft-R accent is dying out. It's most appropriate for period pieces rather than contemporary speakers, though you will still hear it from older speakers today. At the Hermitage - Jackson's plantation - we heard a number of guides who were from the Nashville area. The older ones tended to drop their R's while the younger ones tended to keep the Hard-R American Southern accent more common today.
The second big warning: Don't feel at ALL like you need to go breathy to get this dropped-R sound right. That is NOT an element of the accent, though you hear it in Hollywood films all the time:
Streetar Named Desire:
You can be from the South and still use your voice to its full capacity. It is allowed.