I have a tip on finding a cofounder. I've been looking for the last 12 months and I tried a lot of things, but the thing that worked best is this: Post a job ad.
That's it. My ad sounded like a normal job in every way, with a title like "Director of X". A couple of specific notes: 1) the first line said "cofounder" in it somewhere, and 2) it specified "part-time to full-time, heavy on equity compensation" somewhere else.
The result: Lots of inappropriate candidates applied. But also, my 2 job posts resulted in three extremely excellent team members: a equity-only cofounder, a mostly-equity cofounder/early hire, and an amazing advisor. I have been working with these folks for months and they are very solid.
I also recommend my vetting process: just like a job. That is, I did a phone screen, a multi-hour interview, a little take-home, and I winnowed down the candidates at each stage. With the chosen few, I kicked off a "let's do this" conversation. My pitch was, "I know it's ridiculous, but let's get business married, we'll set up an offsite and start working together full-time... and, if we really need to, we'll get an annulment". That's what vesting is for!
Hope that helps :)