Most successful companies have been started by more than one founder. Even companies that are famous for only one of its founders actually had at least two. While having a co-founder dramatically increases your chances of success, YC actually does fund solo founders. The obvious place to start is people that you know.
How do you find a co-founder and build a great partnership? YC's Catheryn Li (who also built our Co-Founder Matching tool) and Visiting Partner Divya Bhat cover the importance of having co-founders, how to get & vet one, and the ways to build a successful working relationship with them.
Apply to Y Combinator: https://yc.link/SUS-apply
Work at a Startup: https://yc.link/SUS-jobs
Looking for a co-founder? Sign up for Co-Founder Matching: https://www.ycombinator.com/cofounder-matching