When I buy a car the first thing I get for it is a service manual if I don't already have one.

The manual assumes you already have certain basic skills and knowlege. If you know nothing about auto repair it might as well be written in Sanskrit for all the sense it makes.

Experience is the teacher. After you have been working on cars every day for 5 or 10 years, if you have been paying attention and learning, you won't get caught out more than once every few weeks.