Tenacity and willingness to expose oneself (at obvious risk of being told negative things) is requisite to achieving success like this so quickly (and probably also when done slowly).
If you aren't willing to hop on a demo of your product via video chat with a potential customer, per their request, you're directly lessening the chances of that product's success. With that said, once you realize that without marketing or sales, nobody will see your beautiful creation(s), you quickly realize the need for such. Personally, this lead to a desire to learn, practice, and master these skills. However, you can easily find others with a seemingly natural affinity for these skills and delegate these efforts to these individuals (whether partners or employees), enticing them with stock and/or salary should you have sufficient revenue and/or funding.
EDIT: I want to make it clear that I am not suggesting solo ventures succeed less often than those with more than one founder. There is research (see that from NYU and Wharton) pointing to exactly the opposite.
Any suggestions on getting better at this side of entrepreneurship?
Practice pitching your product concisely in front of the mirror. Refine your pitch until you don't bore yourself anymore, then go talk to prospective customers knowing that a majority of the time you will fall flat on your face. Use those interactions to refine your pitch, tweak or pivot your product, and find out what really resonates with people.
Compare https://dilbert.com/strip/1998-02-14 :
> I realized that what's inside a person doesn't count because no one can see it.
> I didn't realize you were such a philosopher.
> That's my point!
We offer to businesses, have a few pilots, but the slickness of Trennd is probably something we'll copy. It was clearly easy to see how the UI helped here - congratz on the sale too (if you're reading this).
Both could be more engaging.