Personal touch
There are some fine books and website articles that offer much sensible and practical information of great benefit to runners. And it's clearly sensible for curious and enthusiatic runners to educate themselves on all aspects of running. That said, it is rare for top level runners to achieve their success without a major coaching input along the way.
Whatever level you wish to run at, a good coach should enable you to achieve better results than if you prepare either totally independently or by carrying out general training programmes that haven’t been adapted to your particular physical abilities and running history. It's also true that the runner is ultimately the best judge of what their body can handle – so it is important to receive regular feedback on how your running is progressing, both the training itself and the impact on the rest of your daily commitments.
Here is a detailed example of a training programme that evolved for a female long distance I coached for over five years.