It always seems so obvious in retrospect but it's hard to think clearly when you're in the gist of doing it and you have a mountain on your shoulders. Something - how so stupid, I'll admit - that I realized is that even if smart people tell you something, you often need to fail it first to really get it. Pick the right co-founders? It's one of the most basic rules.. but how many entrepreneurs do you know didn't liste…
That was really emphasized for me after my first startup failed. After we pulled the plug, all the advice I had procured in the previous months suddenly made sense.
I think that when you hear advice, it might make sense but you don't really understand it. It is analogous to reading a textbook and thinking you've got it covered until you actually reproduce what you learned. That's when the real learning happens. You just need to buck up and get your hands dirty.