This is true, but learning vocabulary is a long, hard slog that you have to get through to get anywhere with learning most of the other skills. It's something

This is true, but learning vocabulary is a long, hard slog that you have to get through to get anywhere with learning most of the other skills. It's something of a choke point in language acquisition, and your knowledge of vocabulary from related language is going to let you down again and again because you don't grasp all the senses of words you think you know or are fooled by false friends. That said, phonology is neglected. Poor pronunciation makes verbal communication more error prone, something you don't need as a beginner, and if you rely entirely on body language for catching such non-lexical content as emphasis and modality, you will suffer when you talk on the phone. A bit of extra work here when you start learning a language will pay off.