When I teach languages I basically work on the student’s grammar and pronunciation. Vocabulary is also important, and I encourage my students to use the language as much as they can. This can take the passive form of reading, watching TV, or listening to the radio; or it can take the active form of speaking to others in the language they want to learn and writing in the language. This can take the form of a journal. Languages are like the piano. If you do not practice, you will not be able to speak well.
Grammar is the building block of a language. It tells you how to put the words that you know into sentences. Perhaps children can learn a language without knowing grammar, but most adults need grammar to learn a new language.
Pronunciation is important. Sometimes it can determine whether the speaker is understood. For some, communication is the chief goal, and having a really good pronunciation is not that important. For others it is important to speak a language well, and that includes a good pronunciation.
In teaching grammar I just go over the basic concepts and use plenty of examples to instill the concept. If the student already has a text, I can help him or her understand concepts that are difficult for them. Most people today do not have a good foundation in grammar concepts, and with them I explain the concepts. With regards to pronunciation, that can either involve imitating for them the word or teaching rules of pronunciation.