I recently finished reading J.I. Packers classic Evangelism and the Sovereignty of God. I found this book to be absolutely compelling and inspiring. At the end of the book I walked away with a number of confirmed or new convictions.
That methods are relatively unimportant. Packer emphasizes that the message is essential, we must be focused on the content of the Gospel, that it is through faith in Jesus and His atoning death in our place that saves us from the consequences of our sin. If this message is in place and central it seems relatively unimportant what method or tried and true ministry we use. It simply matters that we proclaim Christ and Him crucified.
That God is sovereign should inspire confidence in us. God is at work. He will bless our efforts. There will be a harvest. So we should go out in confidence because it does not depend on our abilities or skills or evangelistic method. The work of God is decisive not ours. This certainly does not mean that we sit on our hands and do nothing rather we recognize that it is God's normal method to use means to accomplish His will. So we are given the message and God uses our proclamation of the Good News as His method of bringing sinners to Christ.
The last thing that I want to mention is Packer's comfort with truths that often make us uncomfortable. The truths that seem to conflict (in this case God's Sovereignty and Man's Responsibility) that we feel as if we must decide to believe only one and reject the other. Packer shows us that both can be genuinely true and that we can trust God to be more complex than any human, and that in His complexity both can be true. Now we get to wait for the time when we are in His presence and all these things are made clear. But we may not care because we are in His presence.