Also, there are many different southern accents so it would help to know where the character is from. Kentucky, Texas, Tn, Ms, AL, Georgia, Carolinas, ect all have different accents. Also, in most southern states those raised in the country will have thicker accents than those raised in the city. Julie's suggestion is good. Just adding a slight southern accent on certain words will probably be enough. Another movie to look at is "To Kill A Mockingbird." The kids who played Jen & Scout are actually from Alabama so their accents were real, although the story doesn't take place in AL so they may have altered their speech a little. In "Fried Green Tomatoes" the little girl that played young Iggy was also from AL so has a true accent.