Genetics & nutrition. Of course genetics are the primary factor influencing the final adult height. However, good nutrition is also important. A well-balanced diet with adequate caloric intake, calcium and vitamin d will help to make sure growth is optimal. Your peditrician should be monitoring growth in regular intervals such that any problems with adequate height growth velocity are identified in a timely fashion.
Not in your control. How tall you are going to be from heel to head is based on a genetic gift from your parents that you can't refund. You can take care of that gift by eating real food, exercising daily. Big tip: learn to look people in the eye when you talk/listen with your head up & shoulders back.You'll always appear taller. Spending too much time with computers shrinks your front chest muscles & shortens you.
Not much if grown. Once you are 2 years past your first menstrual cycle or are a man and 25, you will probably be at your final height and nothing will help you grow more. Factors that influence height are genetic. Usually you are going to be somewhere between your mother's and your father's height. Occasionally you can be taller but it is rare.