In this paper, we develop decision making heuristics for rational agents using artefacts of cognition such as observation, learning and memory. Specifically, we extend previous research in this area by incorporating essential aspects of multi-agent interactions such as building behavioural models via observation, selectively choosing interaction partners and forming cooperating groups by identifying mutual capabilities. In particular, we demonstrate that cognitive capabilities enable agents to successfully identify matching partners and establish cooperative groups in a community of selfish agents with varying expertise.