Perhaps the most essential Do in this case would be to always practice for a couple of hours every day in order to ensure that some concepts are imprinted onto the mind. On the other hand, I’d consider the most important Don’t to be not to learn many different programming languages all at once but to rather learn one at a time, based on set priorities.

I support the other commenter's view. Practice, practice, practice. When it comes to coding, even anything in life, you become better by practice. Don't ever let any challenge faze you. You just learn more, practice more and in no time, that one language becomes a part and parcel of you.