^^THIS! Trust is THE most important factor. Treat this like finding someone to marry, because (sadly) there's a decent chance your startup could outlast your marriage. (Pay attention to that, BTW! Your family is
really important, and unless you've already made a huge mistake, no company is worth losing them over.) Any good/honest partner will be willing to tie equity to milestones - never just toss a big chunk of equity to your CEO/cofounder just because others are stupid enough to do that. (Keep in mind the dictum that in most all startup cos., your equity is simultaneously worthless and the only thing of value the company has, other than your team which is usually there because of the potential for equity. As soon as you're funded, pay people fairly - not top of scale, but enough to keep them happy and loving the job.)
And yes, FWIW, I've been on (and been burned on) both sides of these deals, both as a CTO looking for a good CEO to raise money and get us to market (lost my a$$) and as a contract CEO hired to get a company off the ground. The ONLY thing that matters is the people themselves, and more importantly, their character, trustworthiness, and insistence on being fully upright in all things.
It's much harder to find these people than you might think, and it can be really hard to get rid of a bad one if you screw up. (As the Russians say, "Doveryai, no proveryai - Trust, but verify!")