I don’t think there is a definitive model for evangelistic preaching.  There are guidelines, certainly, but also a real need for flexibility.  You have to flex according to the kind of church you are in, the occasion on which you preach, the kind of people to whom you are preaching and so on.

I grew up in a church context where there was, in theory, an evangelistic sermon every Sunday night.  In many ways it was a remnant from an earlier generation in which people would attend church simply because a service was taking place.  By the time I came along (due to being in a Christian family), our culture had changed.  Week after week the meeting would take place, always to the same crowd of believers, usually without clear explanation of how to respond to the gospel, often without clear explanation of the meaning of the cross.  The format of the service was traditional and probably distinctly alien and uncomfortable for any outsider that might attend.  It certainly did not motivate me to invite non-believers.

I think many churches are more purposeful about evangelistic meetings now (at least in my circles).  More creativity, more “natural” communication, more effort to remove the “cringe” factors.  But one thing is clear – there is not one way to preach evangelistically.  Taking into account the people present, how the meeting has been promoted, the expectations of those who have invited friends, etc. all influences how to preach.  Sometimes a gentle introduction to Christianity that leaves people wanting more is ideal.  Other times it is critical to give a more complete gospel presentation.  Sometimes it is time to “shake the tree” and catch the already ripened fruit by overt calls to decision.

It takes sensitivity, wisdom, faith and courage to know which way to go on a particular occasion.  Generally it is best to present the way you informed the church that you would (because they bring guests according to what they are expecting you to do!)  Ultimately, there will probably be criticism coming from somewhere, but that is evangelistic preaching – never easy, always critical.  There is no simple formula, for there are so many variables.  But at its core the gospel doesn’t change, and the world needs it as much as ever.