My combined experience comprises more than a decade (13 years to be exact) of serving either in sales or marketing departments for FMCG, the Service industry or even teaching (as a teacher, of course).
While involved in all these companies, I was involved with various report writing and professional email communication within and outside with potential clients.
This gave me the confidence that I possess the skill to convey my message confidently and in the right way. 
It is over 4 years since I started copywriting (the first 15 months as a part-timer and afterward as a full-time), and I must feel thankful for my past experiences that led me here. 
The time spent in various industries and working with all sorts of people gave me an insight into how people behave and work in different situations. I observed what these business sectors were looking for and how their competitors behaved.
The power of research cant be underestimated, but this kind of experience gives you a slight edge (at least it did me).