First of all, you should be over 18 years of age and should work under the supervision of a master plumber as it will help you in learning all skills of this specific field.
Along with working in the field, you should also complete 300 hours of classroom theory as a plumbing apprentice which will make you a qualified plumber.
For becoming a licensed plumbing contractor, you need to pass the exam which is necessary to become a certified plumber.
Getting certified will not only give you in depth knowledge about plumbing field but will also earn you a good reputation and people will give you preference over your competitors.
You should have the ability to understand the basic math which will help you in understanding the structure of pipe fittings in any building. It will enable you to fix with the plumbing issues with any type of building quite easily.
While dealing with clients or customers, you should behave in a decent manner as it will leave a good impression on their minds and they will contact you whenever they face any plumbing issue.
Try to become a persuasive communicator as well which will help you in convincing the customers that come to you. Considering the competition in the plumbing industry, you have to use your communication skills which will earn you a competitive edge in the market.