Concerns related to the environmental harm caused by the production, use, and testing of hardware as well as software, are widespread throughout the world. Additionally, there is a problem that the associated subtasks use more power than they ought to. Into this direction, there is a constant drive towards Green Computing since many businesses and organizations are extremely concerned about their carbon footprint and its associated environmental negative effects. The latter is a novel idea that has gained a lot of attention recently and is promoted as a fresh approach towards making computing more environmentally friendly by reducing the impact of computers on the environment. Given that manufacturers, businesses, and individuals have the opportunity to use technology to help the environment through programs and systems aimed at reducing power consumption and saving energy, a practical guide to Green Computing is proposed in this manuscript. This guide offers an overview of Green Computing, a description of its development, as well as a list of its services, depicting the obstacles to its goal. A list of related Green Computing efforts aimed at both large enterprises and individual users, is presented, whereas specific manufacturers and large businesses already performing Green Computing actions are discussed. The aim of this research is to give up-to-date practical guidelines towards a greener and more sustainable environment with reduced carbon emissions that are caused by energy-hungry computing actions and environmentally unaware decisions.