I used textbooks, video lessons, and basic audio input to get to a lower intermediate level in my second language (Spanish), and then a ton of native input (audio and written) and actual conversations with speakers to get further. I don't think anyone can tell you exactly what the "best" way is because our brains work differently. For me, this is the best method for my own way of thinking and learning! I still practice with native speakers, I still focus on heavy input, and I write down any rules that are still confusing to me, and drill them from time to time.

For me, the best way is a mix of consistent practice with native speakers and daily immersion. Speaking from day one (even with mistakes) helps much more than just studying textbooks. I also think combining structured lessons with fun things like watching shows, listening to music, or journaling in the new language makes it stick faster.