With a good coursebook, there is a strong possibility that the language, content, and sequencing in the book will be appropriate, and that the topics and treatment of the different language skills will be attractive.
There’s nothing wrong with omitting lessons from coursebooks.
Determine what will be taught (both content and skills).
Formulate the learning objectives for the lesson (e.g., "at the end of the lesson, learners will...").
Match what will be taught to 1, possibly 2, of the most applicable benchmarks from the curriculum and identify in the lesson plan. If continuing from a previously taught lesson, the benchmark could be the same as the prior lesson.