You can move forward a lot with your freelance career just by being super responsive and super friendly. It's a rare commodity. And freelancing is mainly about relationships with your clients. This and your expertise - that's how I currently see the core of freelancing.
I've been on both sides of the barricade. I'm regularly hired for doing specialized WooCommerce and WordPress development and consulting projects for my clients. And I'm hiring other people to do work for me. I'm not delegating my core business because when you work with me, you work with me only (if not explicitly told else) - only this way, I can be sure about delivering the right quality.
Through the years, I've noticed that one of the essential qualities when working remotely is being responsive and keeping the deadlines.