At the beginning of Jesus' ministry, as told in all four of the Gospels, we see the towering figure of John the Baptist.
We need to look at John's calling, because it is similar to our own. John knew that he had a very important message, but that He himself was less important than the message. What was his message? First, that he was quoting the prophet Isaiah, that God is preparing to do something prophesied but yet new; that God was about to break through in a new way. When he was asked, his response was to point to Jesus, and exclaim "Look! There is the Lamb of God, who takes away the sin of the world!" He even pointed his own followers/disciples to Jesus!
And that is what we need to remember. Our job is not to gather followers of our own, no matter how eloquent and charismatic we are. Our job is to point to Jesus! We do not save anybody; that is God's job, and is why He sent Jesus. Each one of us should have our primary relationship with God. He's big enough, He can do this.
We're not completely off the hook, here--we are supposed to have thought enough and prayed enough to understand something of this relationship; we all have our own story. I used to worry that I didn't have much of a story, having grown up in the church and never gotten very far off track. Over the last few years I have come to understand that I do have a story--God did things with me in my life that were in some cases very dramatic and surprising (and unlikely), and then a lot of God-sightings have been sprinkled across my life. We don't need a cut-and -dried recitation to hit people over the head with; just a natural outgrowth of our life.
The other side is a little scarier. We are "witnesses" 24/7 whether we're conscious of it or not. Everyone who sees us and watches us is seeing who we really are without our mentioning anything special. There is an old question: if you were accused of being a Christian, would there be enough evidence to convict you? Does our everyday life encourage people to want to know more--or not?
John the Baptist came, preaching repentance and the coming of God's Kingdom. Jesus even says at one point that history had not known a man greater than John. However, John himself said "I am not the Messiah;...He must increase, while I must decrease."
We're not supposed to be God--but if someone watches where we're going, will it point them toward God? That's our job!