Basically tell everyone about what you're doing. Tell as many people out there and get the word out.
The more people who know what you do, the highest the likelihood of them trying out your product/service.
For me, I did a combination of things:
Working on my site's SEO (long term strategy) - Guest posting as well as blogging / creating good content for my visitors.
Sharing my content on social platforms + advertising the posts - This costed me money but it brought in users and feedback - allowing me to build rapport with my initial users. If you're considering advertising, check out TikTok, Reddit, and Quora ads. They're a lot cheaper.
I shared my services on Fiverr.
I formed partnerships with other companies that could leverage on my services to increase the value of their offerings. Everytime they got a new customer, they would also bundle my services as part of what they offer - this is a no brainer.