Speaking from harsh experience, if you're not starting out with
any lead developers (in most startups I've been in one is included, even if you're going to outsource, because otherwise how can you judge the quality of that outsourced work?), you really need to concentrate on finding two unless you can find the relatively rare type who's willing to sign on by himself.
Most people are a lot more productive if they have someone to work with, to bounce ideas off of, get reality checks, etc.
I suppose one aspect to emphasize is finding initial people who others will want to work with. You're building a team here, and you need to focus on the special aspects of that in this field. Run---do not walk---and buy a copy of Peopleware by Demarco and Lister (buy it directly from them if not particularly available otherwise). Be sure to read the bits on teamicide, although of course that's merely things to not do.
Probably my bottom line is: find someone you absolutely trust. He's going to tell you "we need to do X, which will cost Y" and you're not going the like the Y. But if you've picked the right person, you'll need to bite the Y bullet anyway. Otherwise your future will be filled will pain and attracting and keeping good people will be hard to impossible. (Many examples upon request.)
Good luck!