Optimization in wireless sensor networks (WSNs) has a vast area of application, and the significance of optimization becomes clearer once the resource constraints have been identified. In Chapter 2, our purpose is to provide brief insight into optimization problems, their significance, and potential solutions. With that in mind, the flexibility of problem formulation and the behaviour of its variables and constraints have been discussed. Moreover, an optimization approach to real-world problems present in WSNs has been explored with omnidirectional sensors, which are often used in the k-coverage solution for the region of interest (ROI). Some application areas seek directional sensors due to its geographical and deployment advantages. To give insight into the relativity of optimization and WSNs, a systematic model has been offered to provide the workability of directional sensors in the coverage problem. The parameters used to describe the modelling of the directional sensors are further applied to estimate the coverage probability. The ratio of omnidirectional to directional sensors been estimated in the solution. Further suggestions have been made about the orientation of the sensors and simulation result has been given to investigate the effect of sensor radius and offset angle value on network performance.