We show that two incremental power heuristics for power assignment in a wireless sensor network have approximation ratio 2. Enhancements to these heuristics are proposed. It is shown that these enhancements do not reduce the approximation ratio of the considered incremental power heuristics. However, experiments conducted by us indicate that the proposed enhancements, reduce the power cost of the assignment on average. Further, the two-edge switch enhancement yields a power-cost reduction (relative to using minimum cost spanning trees) that is, on average, twice as much as obtainable from any of the heuristics proposed earlier.