Ask HN: How to learn marketing and sales as a solo entrepreneur?

Hello, I failed with a several products that I built (easy part for devs like us) and then I didn't know how to get the product in front of customers, how to commercialize it, how to increase amount of users, etc.

Many of you succeed in this field, so I'm genuinely curious how to learn it? What are decent learning resources out there?

Thanks in advance