How to become a Professional Mechanical Draftsman?

First learn and understanding the basics of drawing, standards, Dimensioning and Tolerances, mechanical systems, piping, various standards, etc. Then learn and get proficiency in design and draughting softwares like AutoCad, Solid Works, Catia etc. Practice KAIZEN  ( constant and never ending learning) and learn daily. proficiency is not a goal, it is a journey. Try to learn every day. Find a good course and enroll. Also self study is equally important.