CGretired gave you some good advice on pull-pull; do not have a lot of tension on the lines, as he said, just enough to not have any droop. Just as important, have a little positive Ackerman (that is where the line not being pulled becomes a little slack as you move off neutral position). Get that Ackerman backward (where the line not being pulled gets tighter the farther from neutral you get) and you can quickly ruin a servo and will increase current drain on the battery.