I see a lot of churches trying to address evangelism through programs and events and they can be useful tools, but I've always found personal relationships to be the most effective way to reach people.
I just make friends with people. I put myself in situations where I can meet people, like joining a sport/interest/study club or group. I befriend people and I invest in them: time, energy, prayer, me. I'm always open about my relationship with God and over time I get to share more and more. There have been times I've spent an incredible amount of time with someone over a period of 6-12 months and they've come to know God. From there it's snowballed. They've been excited about their relationship with God and shared it with their friends who have shared with their friends. I never intentionally set out to "build a church" but I see people that need God and my heart goes out to them. Pray for a heart for the lost.
When I was 16 I started sharing with my sister's boyfriend. Over time he came to know God and then his bestfriend started coming over to our house and he too became a christian. Within a period of about 12 months I found myself running a youthgroup of 40 teenage boys, all new Christians, desperately in love with Christ. When I moved to a new town the process started all over again with the same results. I've found that for this sort of evangelism to be effective you really need to be prepared to have an open house policy and to spend a lot of time with people. Essentially we're discipling people.
Now that I'm older I'm more interested in helping to equip others to do the same. I figure my "job" now is to make myself redundant. If I can "train" someone to do what I'm doing I can leave them to it and go and train someone else. I like to use the acronym BONDS: Bridge Building, Outreach, Nurturing, Discipleship, Service. Without even knowing it - that was essentially the process I was using. I'd find a way to build bridges with others, I'd share Christ, I'd study the bible with them, I'd teach them and I'd let them loose for the Kingdom. As a larger goup we can institutionalise the process too - 1.Run events and provide services for the community. 2. Provide opportunities for people to hear the Gospel. 3. Run Bible studies for new believers, invite them to church. 4. Run small group fellowship programs like prayer cells. 5. Get people actively involved in serving. Everyone in a church should have something to do. We're a body after all.
I hope this is helpful.