How important is "branding" for solopreneurs?

I'm not sure about “branding” per-se, but I think it can be really helpful to get out there and let people know who you are and what you're doing. Always good to have people around that's going through the same thing you are to bounce ideas off of or to share what worked/what didn't etc. I find Twitter to be a fantastic tool for that.

It's everything. You need to learn how to build an audience before you build a product.