Here is a list I came up with while attending our church's recent evangelism conference for Shavuot (Pentecost - Feast of Weeks), The list comprises some of the governing principles I consider to be vital and practical in evangelism.
1. Pray initially and unceasingly (for self preparation and opportunities).
2. Live in such a way that causes others to raise eternal questions.
3. Be ready at all times to give "an account for the hope that is in you."
4. Be opportunistic in short-term opportunities (bus, plane, passing conversations).
5. Be patient in long-term opportunities (work, gym, church).
6. Know your sinner's theology/religion (Jew? flailing "Christian"? Atheist?).
7. Emphasize your ongoing and past sin - don't whitewash your sin and in so doing nullify the Savior's sacrifice. Your perception of your own inherent sinfulness and ongoing war with the flesh will speak volumes to the self-righteous and skeptics alike.
8. Use diverse methodology - C.S. Lewis' "Liar, Lunatic, or Lord" method is awesome, but it is not the end all method for every situation. All sinners have one antidote - namely the sacrificed, risen Christ - but not every sinner has the same sinful symptoms. For a religious Jew who rejects Jesus as messiah a theological, historical argument is most likely the best starting point. For a nominal "Christian" (= unsaved secular person with religious attachments) who doubts the legitimacy of established religion and promotes his own righteousness an approach grounded in showing their reprobateness might prove beneficial.
9. Address specific sins as examples of a larger, deeper problem not as a specific problem that can be taken care of individually. The difference between being a good person who "just" does bad things and a bad person who is incapable of doing righteous (God-pleasing) things. The remedy is not "stop doing these things" and "do these things instead." Rather the sinner should be told "you can't stop doing bad things - because you are evil" (that's the point) the only answer to your problem is that God has nailed your sins to Christ's cross proclaiming victory over death and the demons of our realm.
10. Don't sell a reprobate sinner a "rebate-filled" gospel (yes, that's the kind with a little "g"). Emphasize the costliness of Christ's death for both the sacrificed One and His Father. Highlight the abundantly high cost of obedient abandonment of self and adherence to the demands of the Savior.
11. Champion all aspects of the bloody, stained, murderous cross in all its gory details and theological ramifications, but never, ever forget the proof of its effectiveness. The resurrection of the One who claimed perfection, oneness with the Father, Messiahship, kingship, and most of all proclaimed victory over death.
12. Never worry about destroying a non-believer's faith in their religion, self-confidence/self-righteousness, or their family standing. These often are by-products of saving faith as the Lord makes abundantly clear. By using such as these as excuses for not presenting the Gospel or lessening its severity we in effect marginalize the decrees of the Son of God and the high price associated with the gift of salvation. This one applies directly to Jewish, Hindu, and Islamic evangelism.
13. Dismiss the temporality of the typical salvation message ("pray this prayer and heaven is yours") by emphasizing both its immediate and ongoing effects (initial change and gradual shift towards holiness - Justification and Sanctification).
14. Give the Savior his proper place of primary object in the sinner's wanderings. Heaven though wonderful and Hell though awful are insufficient means for salvation. No one has ever avoided Hell on account of fear of it and no one has ever secured Heaven's citizenship due to their desire for it. Salvation can only be received by seeing, desiring, and treasuring God's risen first and only Offspring.