Get a baseline. It’s a good rule of thumb that will rarely steer you wrong.
It puts the “fail fast” mantra in a more productive frame. (Not that anything is particularly wrong with that mantra.)
So what does “get a baseline” even mean? A baseline is putting something on the board. If you’re planning a trip and unsure where to go, pick a place, get flight and hotel prices. Now you have a baseline. Go see if you can find something better!
The process of looking for something better will also help you better understand what you actually want because you’ll have to compare two things (the baseline and your candidate) and reason about which one you prefer.
Trying to find a water softener? Pick one. Then notice that there are different sizes. Research that parameter. Pick a new baseline. Notice there are different brands. Research the differences, and maybe update your baseline.
How “good” the first baseline is is not especially important. As long as it’s somewhat within reason. Jordan Peterson wrote a guide to writing essays that I read a long time ago. At the end of page 8 (of 25) he said something that stuck with me:
Having said all that [the previous 8 pages], here is something to remember: finished beats perfect. Most people fail a class or an assignment or a work project not because they write badly, and get D’s or F’s, but because they don’t write at all, and get zeroes. Zeroes are very bad. They are the black holes of numbers. Zeroes make you fail. Zeroes ruin your life. Essays handed in, no matter how badly written, can usually get you at least a C. So don’t be a completely self-destructive idiot. Hand something in, regardless of how pathetic you think it is (and no matter how accurate you are in that opinion).
This process works for most decisions. Everything from a school or work project to larger decisions like buying a house.
So, next time you’re stuck on anything, just think “get a baseline.” And remember, finished beats perfect.