The first is the development of local or cell groups. These are groups which are able to meet regularly and who have adequate leadership, a leadership which knows how to integrate the various dimensions: human formation, evangelisation and prayer, discernment at its various levels, and catechesis, together with the very important social dimension.
The local group best comes into being where there are some already formed relationships between members; these relationships can then become the means to attract and include new members.
Again a local or cell group whilst engaging in various activities and even organising events for others, needs to be person-centered. That is to say, the group exists primarily for the formation in faith of its members, and to enable them to support one another as people of faith.
Another factor which supports this kind of initiative is the character of the venue. The most important ingedient here is that the group is able to make the venue its own - that it becomes a place where they feel at home because, in a certain sense, they have made it into a home.
The three main ingredients for the ordinary life of the cell group are the social dimension (food is a very good way of establishing this), prayer and some specific formation input.
You can see this form of apostolate with young people in many places both inside the Catholic Church and also in the Evangelical churches. How do you get a cell group going? Pray it into being, and look for and form leaders for such an initiative.