When I purchased the Hello Kitty Crochet book by Mei Li Lee, I had thought I was going to start with one of the Hello Kitty patterns (of which there are two). Instead, I found myself working on a character named Sugarbunny and another character named Purin, and in working on these two amigurumi, I learned a very important lesson, which is this: what size hook you use can determine whether or not your project comes to life.
By “comes to life,” I mean something very specific, and the very specific thing I mean is that the finished crochet object develops a character and personality that is separate and apart from the crocheter.
Here is how Purin appeared in the early afternoon still waiting for his back crochet paws to be attached:

And here he is just minutes later with his paws in place and ready for me to, stuff him, finish the decreases, and then weave in the final end:

With a bag of poly fill at my side and a crochet hook that works especially well for stuffing, I did exactly that, and soon, Purin was completed and ready for adventure:

I was pleased at how well Purin sits up all on his own without my having had to insert any additional armatures. I credit this to two things.
One is the design which is it’s own kind of perfection. The other is that I learned from a mistake I made.
My first effort at crocheting from this book was an absolutely adorable pink sugarbunny, and when I crocheted it with my 4.0 mm hook, I was perfectly pleased with it, but when I used the same hook and the same weight yarn to make the Purin pattern, the result was less amazing, and I ended up frogging it and using a 3.25 mm hook, and that change suddenly made Purin look more like it was possible for a yellow crocheted golden retriever to come bounding through the door.
It was then I decided that I needed to frog the pieces I had made and start fresh. Here is how it looked before tidying up:

And here is how it looked thirty minutes later:

In a perfect world, I would have selected the exact right hook from the very start to make a crochet amigurumi that comes to life , but the world is not perfect, it is just perfect enough, and sometimes just perfect enough is the best a person can do.