Sales isn't easy to learn, especially when you have beginners luck and then hit a wall. This book, from the Sandler Sales Method, gives a good overview of the approach, and why it can be easier to sell when you first start, than once you get into it.
His continuously-updated books page, where every book he reads gets a 1-10 rating and a "Why Read it" note; the book links carry his Amazon affiliate tag. The page carries no publication date for individual entries — its own metadata gives article:published_time 2012-12-16 and article:modified_time 2020-10-28, and books were added across that whole span. (undated page)
2020-10-28·jasonevanish.com ↗