"Peace I leave with you; my peace I give you. I do not give to you as the world gives. Do not let your hearts be troubled and do not be afraid."
In my observation and experience, Christians who have been broken in life are generally the first to recognize others who have been broken. They are also the best to minister to the broken. Regrettably, it has also been my observation that most Christians who have not been broken are more concerned with getting ahead in life, looking after themselves and their families than they are withlooking for the broken and the brokenhearted. Maybe the Good Samaritan helped because he understood what it was to be an outcast.
So, when you decide to use your church foyer for more than a gathering place, recruit from your members those Christians who have known real bruising in life. (This may be a bit of a task, however, especially if you have not been broken yourself because they may not feel comfortable opening up to you) Work with them to develop a program through which they will wander around the foyer whenever the church is open for services and look for visitors who are broken.
A spotter needs to be someone given to hospitality, that is, given to turning strangers into friends. (Hospitality) This makes it easier for a spotter to establish a rapport that will be continuous. Continuity is one of the lacking ingredients today, particularly among evangelicals where it can often look like a production line.
If you have done your Foyer homework you will by now know that people do come into your church. When spotters get to work and the church prays, your spotters will soon develop quite a network and this network will need to be adequately managed. So, since by now you have good feedback mechanisms in place (yes?) you will utilize feedback from spotters' networks to improve even more your reception of visitors.