Over the past two decades Wireless Sensor Networks (WSNs) and their applications have been the topic of many studies. WSN is a network responsible for collecting, processing and distributing wireless data to the intended database storage center. Because these sensors are usually installed at remote sites, despite the recent advances in the WSN technology, its applications still face significant challenges. Out of these, network security threats, network architecture, data collection, deployment and network coverage rise as the major concerns. Therefore, these five issues have been well studied in the literature. The main purpose of this paper is to detail these issues and elaborate on possible solutions.