Do a side project that will require you to write a lot of javascript. Try not to use libraries like bootstrap that do a lot for you.

If you write a lot of js, you'll probably write messy js, but you'll understand how it can so easily get out of hand.

Then read a lot of code and the other resources people have linked to here. Having done a lot from scratch will motivate the solution a lot more.

You will have actually run into the problems they are telling you to solve and understand why it's good js rather than just taking their word for it.