About 50% were through my personal network, the rest came from various online sources. Angellist worked really well for me, I highly recommend trying them if you're looking for early stage startups. Linkedin was overloaded with recruiters, I got little use from it.
Thank you! When my Marine Corps contract expires in about ten months I'm going to be looking and both the advice to try AngelList and the confidence that it will be alright will be a huge help.