My name is Ren from the Shopify support team and I can definitely point you in the right direction. Freelancing for Shopify is called being a Shopify Expert. Experts are partners that are well versed on our platform and offer a range of services on topics such as store building, marketing, content writing and others like the ones seen here in the Expert Marketplace.
At this time, Shopify isn't accepting any new applications but you can sign up here to get notified via email of any updates. In the meantime, it doesn't hurt to familiarize yourself with Shopify Expert best practices and guidelines as outlined here to help you prepare for submitting an application when the time comes.
Hope this helps!