I believe that you need to keep in close fellowship with Christ via prayer and bible study so that you will be more sensitive to the need.
I believe that people will look at how you live your life, but you must be open about your faith or they will not know that you handle life well because of Christ. Only that you handle it well.
I try to live with Christ every day. Last night as I handed out Halloween candy I was happy, cheerful, genuinely pleased to see the neighbors, and I spoke to each of them for a few minutes just in a nice neighborly way. Then I realized I was telling people, "God bless you," as they left. It was coming from my heart and soul, not something I planned out.
When I do a kindness, I try to remember to give Christ the credit. When I had money to give, and I heard people were in need, I gave them the money, not loaned it, and said, "I think Christ wants you to have this. Someday, when someone else needs help. Please help them in Christ's name."
When something wonderful happens, and I share it with others, I will say, "I feel like God is really looking out for me lately."
I carry my bible with me most of the time. If people ask me about it, I tell them why I love it.
If I hear someone knocking Christians, I will say, "Excuse me, but I am a Christian, and I'm sorry you feel that way. Can we talk about the difference in what Christians do and in what Christians should do?" Or, "Please, don't judge Christ by the actions of Christians." Sometimes I make it a joke. "I won't judge all Democrats by the ways of the Kennedy clan if you won't judge all Christians by the ways of those you dislike."
I have approached people close to me and said, "I love you so much, I know that you think I'm nuts to believe in Christ, but I also know that you have said you wish you had whatever it is that lets me have so much peace in my life. Can we talk honestly about why I believe in Christ?"
You should not be ashamed of that early zeal you had in life. That kind of "I don't care if I offend you," zeal is what the early church had.
Please, don't fool yourselves into believing Satan's lies either. If you are afraid that the message of Christ will offend and you let that silence you, you are acting ashamed of Him. If you think only living a good life is the same as telling others about Christ, you've fallen into a humanistic lie.
You have to let people know that the source of your joy and peace is Christ or you are denying Him as surely as Peter did that day.
Think about this in terms you can relate to more easily. If you loved a spouse or a parent, and they said they love you back, but they never mentioned you to anyone, never introduced you to anyone. How would you feel about it?
If they said, "Well, yes, I'm glad that you like my clothes. I'm glad you think my house is clean. I'm glad you want to live more like I live," but they never once told others that you were the reason for the clean clothes and the clean house, how would you feel?
You don't have to be "in your face" or "offensive." You can be firm and kind. You can say, "I respect your right not to believe in Christ, but please, respect my right to believe with all my heart." You can say, "I'm sorry that you find Christianity offensive, but I don't deny you the right to have your silly slogans and pictures of people you admire and love in your office. Please don't deny me my right to have bible quotes and crosses in mine. They remind me of the fact that my life is 10,000 times better since I've come to know Christ."
You can invite them to join you in fun activities at your church.
You can give gifts that fit what they tend to want, and add a card with a scripture, or add a bible, or add a Christian CD to it.
I used to include a "family bible" in every wedding gift I gave. I'd write notes in them, to the non-believers, that said, "I know you don't share my faith, but when people marry you should share things with them that helped you in life, and nothing has every helped me more. So along with (whatever the other gift was), I want to give you this. If you do not read it for faith, read it for literature."
Because I know, you cannot read God's word and not be moved by God's word.