Decide the overall goals of your course before you begin. If your aim is to help your students pass a specific test or exam, then this is your ultimate goal. If your aim is less formal, such as making students more comfortable with using the English language, then you can plan your lessons around this.
Divide your goal into sub-goals, dependent upon the number and duration of lessons you will have. If you are running a twice-weekly six-week course, then you will need to write 12 sub-goals. Write each of these on a new piece of paper, and this will form the basis of your lesson plan.
Use the following format for lessons. Begin by teaching the students briefly about a new idea you are introducing. Then have the students practice this by speaking amongst themselves, in smaller groups. Finally, practice this new skill as a group, perhaps by working through a problem written on the board, such as translating a new piece of text.
Use resources to help you teach. Have the students watch the news in English, or give them a short magazine article to read for homework. Although the course is based on speaking English, reading and listening are skills which will improve their oral ability.
Conduct most of the lesson in English. This will help students become used to hearing English, and understanding from the context what is being said. Only use other languages to explain concepts that you cannot explain in English. Although this may be hard for students at first, their progress will be rapid.