How Do I Get Good at Being Pithy and Selling Ideas?

The first person to actually point out my real specific knowledge was my mother. She had already observed that every time we walked down the street, I would critique the local pizza parlor on why they were selling their slices a certain way with certain toppings. So very often, your specific knowledge is observed and often observed by other people who know you well or revealed in situations rather than something that you come up with.