With the maturity and development of Wireless Sensor Networks, a large body of research is being assembled and several routing protocols have been developed for wireless sensor networks. Routing metric is very important for the performance of wireless sensor networks. But a little attention has been paid by the researchers to the evaluation metrics and design principles for routing protocols that should never be neglected while designing and evaluating routing protocols for wireless sensor networks. This paper depicts some vital evaluation metrics that are essential while designing, developing and evaluating the performance of routing protocols for wireless sensor networks. This research is an effort towards hoarding all the general metrics and guiding the researchers for designing efficient, professional and valuable routing protocols. © 2011 IEEE.