The following steps is how to prevent respratory infections and disease.
a. Wash your hands with soap and water every day.
b. Cover your mouth and nose when coughing and sneezing. Use the bend of your arm to cover these areas and don't spread germs. If you do use your hands make sure you wash. 
c. If you are coughing up mucous that is another color than clear and is running a fever consult a physician. 
d. Make sure you get a flu shot every year. This will lessen your chances of being sick. Also get a pneumonia injection every seven years.

Make sure you have a physical each year which includes a chest xray in order to prevent any problems.