In Wireless Sensor Network (WSN), Energy is a scarcest resource of sensor nodes and it determines the lifetime of sensor nodes. These sensor nodes are battery powered devices. These small batteries have limited power and also may not easily rechargeable or removable. Also due to long distance between sensor nodes and base station in WSN, large amount of energy drains out. Thus energy is a big factor in WSN to be considered. Maintaining energy levels of sensor nodes is a crucial research topic. Various techniques have been invented to optimize energy level of sensor nodes of WSN. As genetic algorithm is best clustering technique and graph theory is best for finding the shortest path for routing data.