[aardvark179]

I personally got there by treating bugs as problems I could try and ask questions about until I had a smaller more precise bug. So either I work out something to ask and answer about the nature of some output, or I try to ask and answer something that helps me more precisely pin down the bug.

Sometimes that can be turning an intermittent problem into something I can reproduce consistently, and sometimes it can be constructing new test cases and seeing if their results match my hypothesis.

It helps to either have a good memory, or to keep notes so you know what you’ve already explored and tested, and it’s something you get better at with practice. I spent several years on third line product support working out what was going wrong for customers, producing hot fixes, and working with devs to turn those into proper fixes in the next version.