There are tasks or items that seem to be really important due to it's seemingly large impact if not addressed (immediately). But in reality, can be can be easily addressed later with little to no consequences. The only real way to identify them is to learn from direct and indirect experience from other startups.
TL;DR There are 3 kinds of advice that can be dangerous and needs extra care when considering. Logical advice, indirect advice and direct advice. What makes them so potentially dangerous is that they are easily disguised as great advice when in fact they are not.
TL;DL - To be able to charge for POCs in markets that typically do not pay, structure your POCs so that the customer gets value even things don't work out. And don't call it a POC.
Data driven decision making. Everyone talks about it, knows its critical and says they're doing it. But when push comes to shove, and decisions need to be made, as many would have experienced, it's far from straight forward.
There has been much said and written about good and bad ideas in the startup world. Most notable and influential to me being Paul Graham’s essay around its counter intuitiveness  and Peter Thiel’s Venn diagram of ‘looks like a bad idea’ and ‘is a good idea'.