Share the good news with others. But don't wait until you're "perfect" or "know a lot about the Bible". Nobody is perfect, and all Christians are on a life-long journey. Be bold, let Christ fill your heart with joy. Communicate that joy to others. Let others know how much you like being a Christian, worshipping with others, studying God's word, and what a big part of your life the church is.
If you are the timid type and a bit unsure of yourself (as many of us are), try little things first. Wear a piece of jewelry that has religious implications to work. A cross necklace, a "fish" tie tack ... you get the idea. And wait for the inevitable questions. Speak of church worship, special church events, and retreats just as casually as you would about what movie you saw the last week or two. Be casual. Be yourself. But include the religious parts of your life when you talk with others.
Proclaiming the Gospel - a perspective by a former Catholic (now Protestant).Some other ways to spread the Gospel
Web sites, which reach an entire world, are another means of spreading the Gospel.
Volunteer to hand out religious tracts.
Invite someone to a special church event.
Invite a new person to church.
Keep a few "extra" small (hand-sized) New Testament Bibles at your home and work -- you never know who might like to have one. They are very inexpensive (a few dollars).
Invite someone to come a Bible Study group.
Start a home Bible study group.
Help "canvas" a neighborhood. A door-to-door ministry can reach people not normally reached by other methods. Just remember that many people resent "pushy" approaches.
While giving someone a ride in you car, play (not too loudly) a CD or tape of Christian music or put on a Christian radio station that you like. Don't "inflict" the music on anyone, but if you normally listen to it yourself, don't hide that fact when you have company.