Something I still wish I had done for my current startup is pitching the idea to the companies it can benefit most and offer them to work on it freelance for half your usual rate while keeping full IP.

That would allow you to work on your startup, validate the idea and providing income.

And if it doesn't work out you've learned a lot just by having a couple of talks with highly relevant influencers in your target market.

I haven't read it yet, but Never Eat Alone might apply well here...