For many years I've wondered how someone gets to be an airline pilot. Through research, personal experience, and friends I've learned that there is no 'one true path' to accomplish this. One of the main reasons for this is because there are so many different types of aircraft that have almost limitless applications from cargo transport to scientific research. Before you start down a path, it's always wise to determine what your goal is.
Even though there is no 'one true path', many pilots will start off in a similar matter. The most common two methods are civilian flight training and the military. Civilian flight training can begin as young as 16 years of age, while military flight training requires a 4-year degree because pilots are required to be commissioned officers. Military pilots will normally gain the hours necessary to fly for an airline or corporation during their time in the service, which makes for a much easier transition into civilian aviation.
People who do civilian flight training, however, can build their hours any number of ways. One of the most common ways is to become an instructor. A certified flight instructor (CFI) can log the hours they spend training prospective pilots, just as the trainees can log the same hours. Once a pilot's license is earned, pilots will most likely then continue training to earn their instrument rating. Instrument ratings are a requirement to fly as a commercial pilot.
Another way pilots build hours is to tag along with other pilots or to fly cargo, but in my experience and from I've learned the best way to build time is to instruct. My best advice is to get your private pilot's license, then get instrument rated. After you become instrument rated become a certified flight instructor. As a CFI, you will not only accrue much needed hours, but you will be earning money that can be put towards your next goal. I would suggest earning a multi-engine or commercial pilot rating as your next step. After each rating you earn, continue to teach until you have the necessary ratings for your desired career path.
By the time you reach this point you will have the next step of the specific goal that you are aiming for in your sights, as well as a lot of accumulated hours to put on your resume. You will know exactly which path to take next to help you reach your goal.
I have many pilot friends, many of whom were military pilots as well as a few who worked their way up through the ranks from no experience to captain at major airlines flying some heavy metal. All of them had one thing in common though: they were instructors.