What is the principle of capitalizing expenses?

Craig Brown, a mechanic, is planning to open his own car repair shop. He has selected the location, the kinds of cars that he will service, and the number of people that he will employ. However, he needs some help with the capitalization of the machines that he needs to buy, and how he has to depreciate these assets. He approaches you, an accountant friend, to help him understand the fundamentals of capitalization of expenses, the various depreciation methods, and the impact of this depreciation expense related to his assets on the financial statements. You use a former client and other businesses in the industry to prepare a report explaining these concepts to him.