Testing can be more art than science. Our first boy was a model citizen, the second was a nervous boy so I did this.
Got all the other cats out of the room, laid out everything in front of him so it wasn't a big surprise, sang a little song, rubbed his nose and ears. Some people use a lancet device, I free handed only because that's what I was taught. He also loved having a warm wet paper towel rub later but obviously don't soak him.
Whatever works for you is what matters, they know it might hurt so trust is everything. Some people have had to swaddle or cocoon their cat in a towel but that's only when nothing else works.
If you read or hear somewhere about testing the paw pads yes it's been done but that's a whole different thing. Best of luck.