Don't get it until you really need it

The principle: Don't create or buy something until you know from actual practice exactly why you really need it.
 
This is also known as "You Aren't Gonna Need It"

When people are starting on some endeavor they often put significant effort or money into buying or making things that they think they will need.  However, when it comes time to actually using these things it often turns out that you don't really need it after all, or it's not nearly as useful as you thought it would be, or you need something very different than what you thought you would need. And all the time, money and effort put into acquiring the thing turns out to be wasted.

On the other hand, if you wait until you know from experience that you actually need something, you can acquire exactly what you really need, and you will know how badly you really need it, which will give you a good idea how much time or money you should spend on it.


An example from hiking. I used to spend a lot on hiking boots because I thought I needed them because, by gosh, everyone else used them so they must be neccessary.  Then I experimented with hiking in tennis shoes and sandals, and found that it was more comfortable, I got zero blisters for a change, I suffered fewer twisted ankles, and it was cheaper.  I would have been much better off if I had started out hiking in just whatever shoes I had, and only purchased different shoes when and if I experienced actual problems.