In this paper, various multi-antenna dual hop relay networks are studied over flat Nakagami-m fading channels. The studied scenarios include transmit diversity techniques such as orthogonal space-time block coding, maximal-ratio transmission, and transmit antenna selection techniques and receive diversity techniques such as selection combining and maximal-ratio combining, and hybrid versions of these transmit and receive diversity techniques. In order to study and analyze the performance of the multi-antenna relay networks, closed-form and exact expressions for the moment generating function, the signal-to-noise ratio moments, the outage probability, and the symbol error probability are derived. Besides, to provide further insight about the performance of the studied scenarios asymptotic expressions revealing the array and diversity gain are also derived. Theoretical results are approved by the Monte Carlo simulations.