Wireless Sensor Network applications supporting diverse fields have gained a vital focus and interest from the researchers these days. WSN applications are designed to support scalable real time environment monitoring that depends on region of implication. The major challenges in WSN include energy optimization, routing, obstacle identification, security, etc. These constraints need prioritized optimization in fulfilling the requirements of the deployed environment. The sensing coverage of a sensor node is the area determined by the sensing range of the sensor node. Sensing coverage of the network is the collective coverage of the sensor nodes in a WSN. Sufficient number of sensor nodes need to be deployed to ensure adequate coverage of a region. Further, since sensor nodes have limited battery life, it is also essential to reduce the energy consumption. This would help improve the network lifetime and thus the coverage lifetime. To reduce energy consumption in the WSN, some of the nodes with overlapping sensing areas could be turned off using a coverage optimization protocol. In this paper, we discuss various coverage optimization protocols and routing along with energy efficiency techniques for wireless sensor network. We are describing various authors review on proposed techniques for energy efficiency techniques for optimization of wireless sensor network.