You can learn about digital marketing in online courses that exist in educating platforms such as coursera, udemy, etc.
I'm not sure if the normal marketing will work with blockchain, i mean some social networks don't allow us to promote the crypto projects. They have a bad concept about cryptos because it has been abused with scams and Ponzi. So if we want to make a facebook campaign or a twitter campaign to promote our crypto project, they will don't allow us at all.
I think the best way to promote a crypto project is in forums like this one. That's why signature campaigns exist.