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.
The 3 W's of Business:
What - is the problem you are solving?
Who - is the customer that needs this?
Where - are they so you can market to them?
That's it.