Over at CADRE Comments there has been some discussion about whether our changed lives are a legitimate part of evangelism. (See these threads and comments on them: Part 1 and Part 2.)
So what was the practice of the earliest Christians on that? In the Bible, the woman at Jacob's well spoke of her life story as a launching point in talking about Jesus. And I should mention: she was talking about Jesus because she was amazed by Jesus, not because she was amazed by herself or even wanted to legitimize herself. Jesus legitimized her, not the other way around.
There are many people that Jesus healed who are said to have told people what God had done for them. Though if our lives don't show a particular medical miracle, there is a risk that we come across as boasting or self-absorbed to talk about ourselves much.
Also in the Bible, St. Paul goes into his personal life plenty of times -- though if we follow his lead there, it's interesting to see exactly the examples he chooses from his life, and how he looks at them. He talks about not boasting in ourselves, but only in the Lord. He talks about the things he used to be so proud of and how worthless they seem now. He talks about his struggles with his own faults and with unanswered prayers. He talks about the hardships he has endured for the sake of Jesus. He talks about his bona fides and his educational pedigree when he needs to open doors. He insists that, when it comes to humility, he has more occasion than anyone else to be humble, and claims the title Chief of Sinners for his old life before Christ.
A lot of his messages are addressed to those who already shared his faith in Christ. Sometimes there were factions all sure that their approach was the best. Sometimes Christians were boasting their pedigrees against each other to one-up each other and claim the legitimacy over each other. These were the ones he reminded: no matter what our gift is, it is worthless without love. No matter how right our message is, without love nobody will listen -- because it will sound awful. Without love, it easily turns into self-righteous squabbling, and there's nothing spiritual about that.
I think that whether we talk about our lives depends on whether it connects with the people in the conversation. But we certainly don't boast in ourselves, and we make sure we're clear within ourselves that we're not the message.
The greatest message is Jesus' love, the greatest commandment is love, the greatest gift of the spirit is love, and the nature of God is love. The way we deliver that message is with love, or we have already lost the message before we open our mouths.