In this paper, we present an improved power allocation scheme to minimize the outage probability subject to the total power constraint. For the proposed approach, the source power is determined by simplified optimization approach. The remaining power is then allocated equally to the set of selected relays by two proposed relay selection methods, optimal and simplified. Simulation results show that the power allocation with the proposed relay selection method improves the outage performance by both optimal and the simplified techniques. Moreover, the proposed method improves the performance even in the case of small number of relays.