All the other answers I've read so far have been good, but do not explicitly mention a key factor that has helped me learn so much.

Do your damndest to find a person more experienced with you in the language that can offer a code review after you create a mini-project or otherwise contributed to a codebase. I've learned alot on my own but having an objective person who understands the language better & can point out things like 'that thing you did in 3 lines of code can be done in 1 with this syntax in this language' has been invaluable to me.

Tap your professional network if you've got one, find a way to get this as part of your learning. I doubt you'll regret it.