If you're ever going to be successful as a writer . . . you need to start thinking like a businessperson.
Get yourself into the mindset that your writing is a career, your business, and whatever you do is dependent on you.
Replace writing with, say, construction. If you're going to be a successful contractor, you need to get your butt out on the streets and start hussling for some jobs. Make yourself known. Maintain an honest demeanor.
Do you think any other type of self-employed business is different than writing? It isn't. Whether you're swinging a hammer or tuning pianos or detailing automobiles or writing, it's all the same.
Get your mind into the business mindset.
Act like your writing is a business.