I tend to think (at this point in my journey) that the way we live our life generally speaks a lot louder than our words. If people see the values of the Kingdom in our lifestyle, the 2 or 3 words we may drop into a conversation about the Lord will carry a lot more weight than if they hear us preach non-stop, but see us living differently.
In my current workplace (a Christian charity, which employs both Christian and non-Christian workers) I tned to speak very little about my faith; people know I go to Church, some, over the years have picked up rather more detail. However, I like to think, on the whole, I do my job and relate to others with integrity, compassion, fairness etc. etc. - I'm also told I tend to exude an atmosphere of calm (even on days when I'm feeling really stressed out inside!?!) As a result, from time to time, when they have particular worries or concerns, folk come to me for advice - sometimes explicitly saying 'What do you think God thinks about ... ?' On a few occasions, people have even ASKED me if they can come to my Church with me. Something which NEVER happened all the years when I was in a more hyped-up evangelistic-mode!
By contrast, I have a colleague who goes to the same church as me, who is ALWAYS talking about Jesus, enthusing about how great the service was, singing choruses, putting on worship tapes, giving little homilies about what the Bible says about various situations. From what I can gather, most people view her as something of a 'freak', and try to avoid getting cornered by her. One or two folk have specifically remarked, "If she's such a good Christian, how come she does x, y and z?" The general feeling seems to be that she's so insecure in her faith that she has to try ultra-hard to convince herself its true!
I do beleive that, in an ideal world, the majority of witnessing would happen on a casual neighbour-to-neighbour level - 'gossipping the Gospel' someone called it - rather than through consicous evangelistic campaigns etc. If Jesus is really real in our lives, this must show in the way we live and behave, and people will notice the difference - like in Acts 'See how these Chrsitans love one another', and 'these people who are turning the world upside down' speaks volumes. Of course there is a place for preaching and verbal witnessing, but I beleive this is usually far more effective coming out of a relationship of respect etc., than from some unknown preacher behind a microphone. Sensitivity to the Spirit and the opportunities he provides to slip in a word at just the right moment in a person's life is a great thing. And I have to confess I'm not that good at it! But isn't there a proverb to the effect that one word in season is better than a thousand that are not? There's certainly one about even a fool is though wise if he keeps his mouth shut!
BTW I also agree with what has been said about small groups; the Alpha Course has its faults, but part of its success with certain parts of the population is from the small group exploration principle - people are encouraged to ask the questions they want as they develop a relationship with the group, rather than just sitting back and being preached at. Church is one of the few places in the world these days where people still think the way to teach folk is to talk at them solidly for 1/2 an hour or more from a platform, with no interaction! But I digress....
Anthony