Effective sharing is flexible. In 1 Corinthians, Paul encourages us to tailor our approach, though not our message to those we are trying to reach for Christ. Evangelism is meeting someone at his or her level in order to bring that individual to Christ's level without compromising the truth of the gospel. Effective sharing is discerning. Rather than anger someone who's uninterested, it is best to simply present the truth and move on.
Effective sharing is tactful.
A fruitful witness is a tactful witness. Effective sharing is backed by love. This final principle is the most important one we need to employ. Whenever Jesus came into contact with people, He genuinely loved them. Such love and concern will speak volumes before we even utter a word.