The aim of this paper is to fill the existing research gap in the knowledge of the interrelationships between relational resources, the static capabilities associated with the planning and organization of export activity, certain dynamic capabilities—international entrepreneurial orientation, orientation to foreign markets and strategic flexibility—and the achievement of perceived competitive advantages in international markets. The proposed conceptual model is analyzed on the basis of an empirical study using a multisectoral sample of 330 Spanish exporting companies. The results obtained, based on the use of SmartPLS and fsQCA, show that: 1) relationship resources are essential determinants for the development of an adequate export planning and organization capacity and have an impact on the international entrepreneurial orientation of the organization; 2) it is necessary to plan and organize exports well, since the adequate development of dynamic capabilities in international markets will depend on this; 3) international entrepreneurial orientation, orientation to foreign markets and strategic flexibility are essential, directly or indirectly, for the achievement of sustainable competitive advantages in foreign markets. Based on the results and conclusions obtained, the main implications for management are proposed.