I'd been crocheting since 2005 and my first solo pattern was in 07. I basically started when I couldn't find a pattern for something I wanted to make. I knew the techniques for increasing, and decreasing, For making basic shapes, Circle, oval, and triangles etc.
My first solo amigurumi was a tiny pug I made for my grandmother. I pulled up pictures of pugs online and basically looked at common colors. I decided on black and tan.
I knew what shapes to make the legs, little ovals with a open end to stuff. I made the body a closed oval, and the head a circle.
My next ami was a crocheted fish a Koi. I learned how to change colors. And after that a lobster. And then my honeysuckle dragon.
My basic tips: Look up pictures of the animal or item you want to make. Break it down to shapes. Basic shapes. Work a row or two and mark it when you like how the shape is coming. This way if you don't like the next few rows you can frog back to that point rather than rip out the whole thing. And the biggest is to not be afraid of mistakes. Use it to learn! All the good talented designers make multiples of things till they get it just right! That's ok! IF you have to frog or rip out, it's ok! If you start to put it together only to realize you made one leg to long, it's ok!
Making mistakes is human and normal. Don't beat yourself up for it. And don't be afraid to rip out!