A few years ago we moved away from what we called a "Ministry Fair" to a "Volunteer Expo" (I'm sure we borrowed it from another church). We found that the mere label was more understandable and less intimidating for people new to our church and/or Jesus. In years past, we set up large areas using tents or other temporary structures in a designated area on the campus and pointed people to the Expo following services. We experienced some measured positive outcomes in people stepping into the varied opportunities.
This year we opted to create space inside our auditorium where services are experienced. No one had to leave the room. However, we needed to help people visit ministry booths quickly and effectively. So, using tear-off cards in every program (bulletin), guests were invited to choose ONE area to start with and drop their card at that selected table. There they received a printed sheet that provided a bit more detail and information about the next step. That next step might be to participate in an orientation, visit/observe a ministry function or expect a return phone call for an individual conversation.