Im no pro but I can try and pass on some of the things I do know.
Use your sonar to find the depth where the fish are holding. Depending o the weight of your D.R ball you'll have to adjust your depth due to the swing back of the forward momentum(sp) per the speed you're going. I like 10lb weights as they seem to track pretty up and down.
When the 'Queen of trolling' gets home from work im sure she'll be able to give you some better tips than me