I don't know what kind of freelancing you plan to do, but for me the method of moving to freelancing that worked (after two failed attempts) was connecting with veteran freelancers as quickly as possible. I became the technical resource for a creative agency by just calling them up and asking them if they needed technical help. From there it was a matter of being responsive to their communications, helping them look smart in front of their clients by feeding them ideas, and giving them flexibility--trying not to say "no" too often, even after seeing their pie-in-the-sky Photoshop mockups.

Since then, I've expanded my opportunities by reaching out to my competition to build friendships and explore ways of working together.

I found my (limited) corporate background a bonus because I was used to working on a relatively productive team (edit: so I could basically pull a team of freelancers together and bid on a large project as a group of independents), and a liability because I tended to think "I could always go back to the corporate world" instead of taking every opportunity to figure out how I might make self-employment work. It wasn't until I hired a business coach (a former SV corporate guy himself) that I started to learn how to make the whole thing psychologically/emotionally sustainable. There are opportunities to write your own failure narrative around every corner. :-)