Every person is different. I prefer the building relationship method Being friends with someone, genuinely caring about them, knowing their needs, preferences, desires is my favorite way. People can smell "I want you to convert, so that you'll be number 585 I've won to the Lord" a mile away. Plus I think that attitude is wrong. Rather we should want to win people because we love them.
So what I do is get to know them. Where are they in life? Where are they hurting? And then I try to start where they are to lead them eventually to the place where I can share the truth of the Gospel. It may take 10 minutes, it may take 10 months. I'm willing to take as long as it takes because I care about that person.
My model for what I share is:
The Problem (Sin)
“For all have sinned and fall short of the glory of God.” Romans 3:23
The Solution (Jesus)
“But God demonstrates His own love for us in this: While we were still sinners, Christ died for us.” Romans 5:8
How the problem is solved (respond to Jesus)
“If you confess with your mouth, “Jesus is Lord,” and believe in your heart that God raised Him from the dead, you will be saved.” Romans 10:9
No matter what I make sure the above three elements are eventually presented somehow. I rarely witness the same way twice. Though I often use the same Scriptures and illustrations that I have found to be effective. I try to start with A LOT of questions and do A LOT of listening. Here is another method I use. As part of a conversation, I ask the following questions, listen to their answers, and then I am careful to explain how the Bible answers each question.
What do you believe about God? The Bible says: God is holy, perfect, eternal, omniscient, omnipresent, omnipotent and the just judge of the universe. God “commands all people everywhere to repent. For he has set a day when he will judge the world with justice by the man he has appointed” (Acts 17:30-31, see also verses 24-31)
What do you believe about the Bible? The Bible says: “For all Scripture is God-breathed and is useful…”(II Timothy 3:16)
What do you believe about Jesus? (Is he equally God and equally human?) The Bible says: “In the beginning was the Word, and the Word was with God, and the Word was God…The Word became flesh and made his dwelling among us.” (I John 1:1, 14)
What is man’s basic problem in relation to God? The Bible says: “For all have sinned and fall short of the glory of God.” Romans 3:23
What is the solution to that problem? The Bible says: “For the wages of sin is death, but the gift of God is eternal life through Jesus Christ our Lord” (Romans 6:23) “But God demonstrates his own love for us in this: While we were still sinners, Christ died for us.” (Romans 5:8) See also Romans 10:9 above.