There are many exercises you can do once you have finished your warmup. Speed walking or jogging up and down stairs are common exercises to try when you start your routine. You can also do lunges, in which you take more than one stair per step, but go slowly until you master the exercise. Walking up the stairs sideways will work slightly different muscles than when you face forward and go up the stairs. Experiment and find a routine you are comfortable with. Whichever you choose, keep your feet firmly planted on the stairs at all times to avoid injury.