To become a professional diving instructor you need to complete many scuba diving courses, get a lot of experience and dive a lot. It always help if you can speak another language of have experience in other fields, like First Aid, Management, boat skills, mechanics, etc.
To become a dive professional you need to do 2 vital courses the Divemaster and the PADI IDC . The Divemaster course will give you the option of working as a guide, this is a nice job, but the salary is usually lower that the salary a scuba diving instructor makes. To become a scuba diving instructor you need to do your PADI IDC course.
One you complete these courses, you need to apply to scuba jobs around the world. Before you go straight to scuba diving jobsites, try to think carefull about your objectives and about the kind of employement conditions you want and the countries you are willing to travel.
Not all the jobs are the same and working in Australia is very different than working in Honduras or Egypt. You need to be smart and think with your head, and work towards getting the best diving certificates that will give you the highest chances of finding that ideal dive job.
My best advice is to contact people by phone first, there is nothing better than speaking to people, and once you get the proper information then send your application via Scuba Diving jobsites or directly to the dive center.
You need to remember that finding job is not impossible, but it can take time, and once you get the ideal dive job, you need to work hard to keep it. Always be aware that sooner or later you will want to go back home,so when you travel to your diving location, have a plan B. Medical insurance, work insurance and current teaching status is important to improve your chances of finding job.
Try to be patient and don't think your new diving job will be a holiday, some days can clearly difficult, but always remember that any day diving is much better than any day at the office!
So, I know what you are thinking... where to start? Well, like any other diving jobs, start by diving a lot, talking to people and check divers jobs websites, where you can get yourself a clear idea of where are the vacancies around the world. Central America, the Red Sea, Australia and South East Asia are great places to start your dive job hunting.
So good luck and see you underwater