If you need to learn something, two or three books on the subject will get you a really long way.
For example marketing. Read Alchemy, Building a StoryBrand, and $100m Offers. Or others, there’s loads to choose from.
You’ll know more on that subject than 95% of people. Maybe more.
Especially if you follow my magnificent process (that may need a catchier name) ReCorDeR:
Read. Learn about the thing.
Capture. Write the thing down.
Do. Do the thing.
Repeat. Repeat the process for a new thing.