Read Ellen G. White, “A Knowledge of God”, pages 87-91, in Steps to Christ; “Bible Readings With Families”, pages 192-193, in Gospel Workers; and “Bible Work Techniques”, pages 481-486, in Evangelism.
God is working on hearts all around us. If we have the spiritual discernment to see where God is already working, we will regularly observe opportunities to share His word with others. As God prepares the soil of the heart, we have the opportunity to sow the seed of the gospel.
The Holy Spirit prepared the hearts of Nicodemus, the woman at the well, the woman with the issue of blood, the thief on the cross, the Roman centurion, and many others to receive His word before Jesus ever met them. Through the circumstances of their lives and the impressions of the Holy Spirit, they were prepared to receive Christ’s message.
We may have a natural hesitancy to ask people if we can pray with them, share a Bible promise, or give them a piece of literature. More often than not when we feel impressed to share our faith with someone else, it is because the Holy Spirit who has impressed us has already impressed that person to receive our witness.