Another thing worth knowing is how to test a tool before you buy it.
Different tools have very different methods… for example, I was saved from losing a lot of money because I knew how to test a Curta mechanical calculator before buying it (basically you start with all zeros, subtract a 1, then add it back. The readout should be all nines then all zeros again. This tests much of the inside gearing in two seconds).
Testing a hand tool can be even simpler. When I started into DIY I had this manual that had a section on hammers, including the paragraph shown at right. I used this test to select a claw hammer, ending up with a Stanley Hercules that has served me well through countless projects, and as you can see below it passes the test well. And if you think this is not very important, I can tell you that this hammer can drive nails right into anything without slipping or bending them, as a low quality tool often would; you supply the momentum, the hammer takes care of convincing the nail it had better go straight in. A real pleasure to use!