The following advice is from an article in the atlanta journal-constitution newspaper. the link below is for whole article. There is another funny article there about growing them upside down in buckets.

"Almost always I get, 'My tomato has early blight. What do I do?' " says Reeves, host of "The Lawn & Garden Show" on WSB-AM. "The disease splashes up off the ground onto the plant, and by July the leaves turn yellow and fall off." (His solution: Spray with Daconil and mulch plants early on to prevent the disease from spreading.)

Plant tomato plants 8 to 10 inches deep (up to the first two leaves) so that only a few inches of plant are showing, and space them at least 2 feet apart. If planting in containers, avoid overcrowding and use no more than one or two plants for a whiskey-barrel-size pot. Water the plants well and add mulch, such as pine straw or newspaper, to help soil retain moisture and prevent the spread of disease from soil to plant. "Not mulching is probably the biggest mistake people make," Reeves says.

Here is a link that might be useful: tomato advice