I am a college student and I am learning German right now. So I understand the difficulties of learning a new language. I use the same methods to teach my students that I use to learn a new concept myself.
I try to build a deep understanding of the language through essay writing and asking my students to converse in English without being afraid to be wrong. My method of teaching involves taking sentences in an increasing order of difficulty and putting it through all the different cases.
For example, to teach active ans passive voice, I first give the students a sentence with a direct object and ask them to translate that same sentence for all the persons in all the tenses. Then I ask them to add an indirect object to the sentence and do it again. This method might seem a little tedious to some, but I have been tutoring students for about a year now, and this method of doing it themselves seems to really help them remember. After completing this I ask them to write a paragraph in active voice and then convert it into passive voice. From my observation this really helps them understand the concepts.
There's no better way to learn a language than to converse in it and read books in that language. So, I always encourage my students to talk in English as much as they can. Also, being an avid book reader I often recommend books that are at the level of the student.
Making mistakes while learning a new thing is a natural thing to happen. So I always encourage my students to be more confident in themselves and to not be afraid of being wrong.