To become a great marketer you should follow in the paths of those successful marketers who have gone before, going back to the age of direct mail marketing which was developed mostly in the USA about a hundred years ago because the fundamental principles of marketing have not changed as good marketing involves human psychology when people are asked to buy something.
The great copy writers such as Gary Halbert ( The Boron Letters ) and others created methods and sales copy that is still studied avidly today by the best online marketers such as Marlon Sanders who has a deep background in studying offline and direct mail methods which he adapted to the new online marketing medium.
With the development of new social media we still employ similar copy writing techniques that delve into the human mind when presented with a sales offer. Robert Cialdini has written a classic on persuasion marketing called 'Influence' which studies the social psychology of getting people to say ’Yes’ especially in a marketing context. All this old stuff is an example of what you need to consider if you want to be highly successful in digital marketing - see Tai Lopez on YouTube who has a great respect for reading the old classics both marketing and in general.
I mention all this as most people will refer to the mechanics of setting up a website and selling a product or service and all the stuff about generating traffic and that is all essential, but in my opinion some time should be set aside for studying the history and well tried techniques of the business to gain a higher understanding of what is required to reach a higher level.