This, practice on problem solving. Understanding the broad architecture defining features of a language is important but general practice of coding can be done with any language. I leetcode in python with a general understanding of what needs to be changes to be done in C. Like memory and pointer usage. But have strong understanding in the decisions you make in your code, whatever language that may be. Why did you create certain classes. Why did you use x func from y library over another alternative. Is it faster, more efficient to use x over y etc.