"The problem with implicitly salesy evangelism is bad theology, not bad technique, and it requires more than a simple change in method. If you feel like a used-car salesman talking about Jesus, the solution to the perceived lack of authenticity isn't a smoother pitch—it's a renewal of the church. The potency of personal evangelism is, as it has always been, the simple and earnest retelling of what God has done in the lives of his people. Of course, this requires a community to back up our claims."
See the whole article "Jesus is Not a Brand" by Tyler Wigg-Stevenson