I don't mean to be flippat, but what is there to learn? Certainly there are tips and tricks, and salepeople do possess unique talents. But what is so complicated about calling up potential customers and talking about how your product solves a problem you have?
I think the first step is demystifying it. If you wanted to learn a new programming language, you would just "do it": read books, read about the language, practice writing code, etc.
Your phone call will be answered by a person who has no decision making authority. You will need to ask for someone else, and you will need whom to ask. You will also need to know which companies to call. The calling itself maybe not that complicated, but the prep work is arduous. And then you don’t start with “buy my software” you start with “Problem X is a real drag, don’t you wish it went away?”. A lot goes into it.
Learning a new programming language is a low-risk endeavor. Your highest cost is likely to be a book that you buy, if you decide to go that route.
Compare that to a business, where you have to pay to file paperwork that you may have to hire a lawyer to tell you that you did wrong.
You need to know how to structure an articles of incorporation in a good way for your organization, and you only know you get it wrong when it's too late.
You need to know how to raise funds in a way that own't personally bankrupt you.
You need to know how to read and understand contracts.
You need to know how to hire people in a way that doesn't expose you unduly to lawsuits.
You need to know bookkeeping well enough so that you don't need to hire someone for that right off the bat.
There are tons of things. I know that I don't even know how much I don't know, because I've only ever had a small rinky-dink business.
I think the first step is demystifying it. If you wanted to learn a new programming language, you would just "do it": read books, read about the language, practice writing code, etc.