At this point in my career I can literally build anything that can be built. I have 100s of ideas. Why do I tech cofound with you for 25% equity vs just building my own idea for 100%?
My best recommendation is to start your "CEO" job earlier and to land an appointment with an investor willing to invest in your idea and to include your potential co-founder in that meeting. That would make you worth %50 easily.
If the project didn't start yet, I would only take the bet if you have real experience and real companies/champions [1] waiting for your solution.
My company had a lot of startups as customer. Many of them with strong business and technical teams. almost all died. Full stop.
[1] http://www.businessdictionary.com/definition/champion.html
Would you start a restaurant without ever working in one? A bank with no finance knowledge? If you're not a tech cofounder become one. The reality is that a company with a handful of people needs to have every one of those working on their product or they will be at a massive disadvantage to anyone else that does.
Sorry but I've received too many promising proposals, and even in some cases, I was asked to sign an NDA that forbid to compete with the "idea" even without knowing what the project was about.
Nowadays a none tech co-founder is close to useless thanks to companies like YC. They make everything seamless for tech people so why would a tech entrepreneur work for someone else's idea while giving up power and money?