Take the MIT Intro to CS with Python course. It's an introduction to using computational methods to solving problems. Then take the second course.
Then find problems to solve. Lots of them.
Find a mentor.
I had my 15 year old son take these courses (with me acting as tutor). There is no way to describe the transition he made. From wasting his time learning a bit about a language here and a bit about another language there to focusing on one, learning how to solve a range of problems, learning about data structures and more. He cam out of that swinging and capable of approaching real problems (still with a need for me to coach, but a huge step forward).
Then find problems to solve. Lots of them.
Find a mentor.
I had my 15 year old son take these courses (with me acting as tutor). There is no way to describe the transition he made. From wasting his time learning a bit about a language here and a bit about another language there to focusing on one, learning how to solve a range of problems, learning about data structures and more. He cam out of that swinging and capable of approaching real problems (still with a need for me to coach, but a huge step forward).