Where did I learn to "sell" an argument? Well, before finishing college, I spent several years working in commission based sales. I took a turn selling outdoor furniture and another selling men's suits. Where did I learn how to make a presentation fun and engaging? I spent years playing music in a touring band. It took me hundreds of concerts to finally loosen up and have fun on stage. But when I did, I realized that everyone in the crowd had more fun too. And what about making complex ideas easy to understand? I taught middle school for 2 years. I had to learn very quickly how to make difficult concepts easily accessible. I don't think it is a coincidence that now, I teach high school, where I not only have to make complex ideas easy to understand, but I have to "sell" them in a fun and engaging way to a group of people who would rather smash their fingers with a hammer than pay attention. Just in case you are curious, I have also worked at a grocery store, delivered pizzas, assembled medical equipment, worked in a call center, served ice cream from a mall kiosk, and worked on the maintenance staff at a golf course.
What is my point? Simply put: use the tools that you already have. You have a unique skill set by virtue of the fact that you are a unique individual. No one else has your back-story. You possess abilities that you may have never considered helpful for relaying truth and sharing the Gospel. I have learned a lot of information by studying, but most of what I know about sharing that information came to me unintentionally.