So we (me and a team of students) were in Kent, to work with a church in an evangelistic push before Easter. Tons of prep. Lots of nervousness.
But there is really only one thing to remember, and it is from Psalm 51:12-13 –
Restore to me the joy of your salvation,
and uphold me with a willing spirit.
Then I will teach transgressors your ways,
and sinners will return to you.
And that is it. Our power, effectiveness – and plausibility – as evangelists rests solely on the authenticity of our own grateful faith in salvation.
Lose that, and you have lost everything. rest in that, and the gospel will ooze from every pore.
Enjoy your evangelism, because you enjoy the Lord Jesus.