Startup COO job boils down to this:
1. Pick a problem area, and build 0 to 1 yourself. First principles get you pretty far!
2. After it gets going, start recruiting for an experienced leader for the area.
3. Onboard the leader well, nuke yourself out and attack next problem.
Two thoughts: The best startups are masters of asymmetric warfare -- they don't fight on the battlefield the incumbent selects. And, users often understand their problems well but are horrible at suggesting features to solve these problems.