Step 1 - Make a sketch

You have to imagine each step of the animation, and write it, either by hand (most recommended), or using LaTeX. The advantage of using LaTeX is that you will be saving yourself work, the source code of the following image is this, you can use it in any LaTeX offline distributions (MikTeX - Windows, MacTeX - MacOS, TeXLive - Linux) or using a online compiler (Overleaf, CoCalc)

Warning

Do not underestimate this step, if you are not ordered from the beginning it will give you headaches.

It is a good idea to draw each scene, and how you hope to perform the transformations. Again, you can do this by hand or with LaTeX, I recommend using Inkscape with the WriteTeX plug-in, as shown in the following tutorial. This step is also used to write the formulas in LaTeX and avoid typos.