I’ve been trying to improve my coding skills sporadically over that last year or so. Mostly I’ve used Codeacamedy to do this.
The lessons are built around an interactive coding environment where you are set tasks to write, or complete, bits of code and then run them. If you get the right result you progress to the next lesson.
It’s not perfect though, I’ve found several examples of lessons where code is technically correct but doesn’t pass because the Codeacademy validator is expecting a different solution. It is also fair to say that some of the lesson instructions are a bit confusing.
Thankfully each lesson is supported by a Q&A forum which is pretty active. You can usually find an answer there if you’re stuck, or ask a new question if you need more help.
All told I highly recommend Codeacademy for upping you coding skills, and it’s all free!