My church has a problem. Yours might too.
We have around 100 welcoming, friendly, loving, God-fearing people. Those people are pretty great at pouncing on any newcomers that appear (after all, we're not a big church, and it's always a great injection of vibrancy when a new person shows up, not to mention the fact that we also very keen to share the gospel with anyone interested in listening!)
However, once those exciting wonderful newcomers walk out those front doors after the service, they are gone forever.
Not because we weren't welcoming, or the music wasn't to their taste or the coffee was bad, but because we didn't follow up with them. Ever.
I like to call it the Friendly But No Follow Up Trap.