In order to improve my teaching skills I perform self-assessments every so often by going back to my lesson plan and asking myself the following questions: Were students engaged? Were the learning outcomes met? Did I have good time management?; the purpose is to take a step back and become aware of areas of opportunity I might have while teaching a specific course.
Another way that allows me to continuously evaluate my teaching style is by reading students' evaluations. Because of this, I would provide my students with several opportunities to evaluate me along the semester since I believe having only one evaluation at the end does not benefit them at all. It might benefit the following class but for the students might be too late when I realize something is going wrong with the course.