By that time, I had gotten really good at finding problems with cars myself. The cars I could realistically shop for had plenty of material to learn from. This article is for someone who is out of school. Not someone who's broke, but someone who has become reasonably comfortable and aims to stay that way. Of course, your father was right.
New cars take a big depreciation hit the first few years, and avoiding that is financially astute.
Unfortunately, age does not indicate condition. Or, a car may just be ridden hard and never put away, making it feel old and used up by 20,000 miles. Inspecting even slightly used cars requires significant knowledge and experience and, often, familiarity with the specific model in question. Even if you know what you're doing, driving all around your area looking for the right car can consume many fruitless weekends. And once a promising car is found, paying a mechanic to look it over can be either wise or worse than useless.