Ask HN: What skills should I learn for backend freelancing?

I've worked as a backend developer for two years, and I'd like to try freelancing. I'm moving soon (Philly), and I'm wondering where I might spend my time most profitably in the ~3 months before that happens. My current plan is to look for contract work with web dev agencies with a design / branding focus but perhaps limited backend expertise.

If you were hiring me, what would you look for? Are there particular topics, CS or otherwise, I should study? Is it reasonable to start freelancing so early in my career (should I be looking for a full time job?)

Any advice is very much appreciated!