Decide which aspect of math students struggle with most. For example, some students understand basic math concepts, but they do not understand basic calculation. Others struggle with concrete materials while many others have a difficult time grasping the concept of spatial/visual math.
Determine the major course topics. Your department should have a curriculum guide that will aid you in this decision. If not, base your course topics solely on what the students are struggling with the most.
Talk to those who have taught a similar course before. You can get ideas from them on how to best approach the course as well as information on activities and lessons.
Determine learning goals for the course. This is the information you want the students to know before the course is over.
Choose a textbook. This is important as it will help to guide you in determining what lessons you will be able to teach most effectively.
Develop lesson plans that relate to your topics and goals. Consider all different learning styles of your math students and consider incorporating activities that will not only help the students, but let them see math as a task that is enjoyable and necessary for life beyond college.
Submit your course ideas and goals, as well as lesson plans to your department chair for approval.