When Billy Graham was asked to name the three most important things about a mission, he did not include preaching, nor the use of a big venue or big numbers attending. The first thing he singled out was prayer, the second … prayer; and the third… prayer.
Prayer is essential in preparing for mission: we are dependent on God who gives growth. A mission will not bring people to faith unless Christians are actively praying for and making friends with people outside the household of faith. You might like to use the Thy Kingdom Come prayer resources to help you.