To conquer and maintain customers becomes essential to the success of organizations, especially when it comes to small and medium enterprises (SMEs), in particular firms selling services. To materialize activities for the achievement and maintenance of customers based on the principles of Relationship Marketing (RM), one can assume managerial practices developed in various hierarchical levels: market management (MM), strategic management (EM) and operational management (OM). This research is an exploratory study of multiple cases, conducted in nine 'per kg' restaurants in business for more than ten years in São Paulo. Through qualitative research were discovered practices developed by managers in order to conquer and maintain their customers. The study presents results, which activities to build the sustainability of relationships between businesses and customers, develop the frontiers of "trust" and "satisfaction" of consumers, which is certain competitive advantage to the organization, from the customer loyalty.