Most of the time you will find yourself sharing your faith with people you know-family members, people you work with, friends, neighbours-people in your relational world. So the first thing is to build good relationships with these people and live your Christian life in their midst. And when you do share your faith with these people, it will likely be only short pieces at a time, arising out of life circumstances and daily conversations.
When the appropriate time comes, start by telling your own story-your testimony of how you became a Christian and what it has meant to you. But eventually you will need to go further than that and actually present truths from the Bible. Learn some Bible verses that show people God’s plan of salvation. Learn how to open a spiritual conversation or turn any conversation to spiritual matters.
You can actually find seminars, books and short courses on how to share your faith. All of these are helpful, because they give you some tools and a track to run on. But don’t use a canned approach. Be authentic and talk to the person in normal conversation, not as someone trying to go through a formal presentation. Treat people as people, not projects, or simply as candidates for salvation. Make friends with non-Christians.
Be friendly. Be yourself. And remember, you don’t have to know everything. You can say, “I don’t know, but I’ll try to find out.”
Above all, pray and ask God to guide you.