I think vocabulary is king when learning a new language. No matter how good your grammar is, without vocabulary, it is impossible to express ourselves in our target language. Even if your grammar is not perfect, it doesn't matter, people will still understand you. I used to try and memorise new words in my learning language (Chinese) and their meanings in my native language (English). But I soon found that it was not an effective method. I always forgot the word and often struggled to construct sentences with the new word.  Now I don't focus on words in isolation anymore. Instead I try to read and listen more from native speakers. When I come across a new word that is useful to me or commonly found, I focus on the whole sentence. I write the whole sentence in English in my software and test myself to say it out loud in my target language. I learnt the meaning of the words incidentally while learning the sentence. This method is working well for me so far.