Right now in my online photographer's mentorship program, we are working with models and guidelines for composition. The most interesting and detailed one is the Golden Ratio, also often called the Golden Mean or the Golden Spiral.
It is based on Phi, a proportion or ratio that occurs everywhere in nature and has been used by artists and architects at least since the classical era. The Greeks used it to build the Parthenon, but it was Italian mathematician Fibonacci of the Middle Ages who wrote about the numbers in a widely acclaimed and used book about mathematics.
The Golden Ratio is 1:1.618. It can be turned into a grid, a spiral or a series of numbers. Just Google "Golden Ratio" or "Fibonacci numbers" and you will find dozens of examples, not only of how to create a grid or spiral but of where it occurs in nature and how it has been used in art and design.
My favorite is probably this one: Doodling in Math: Spirals, Fibonacci and Being a Plant
I did not get out a ruler to check, but I'm pretty sure the Golden Ratio is represented in my "orderly ivy" in the sizes of the leaves, in the sizes of the lobes of each leaf, and in the lengths of the segments of the vein network.
If you get out a ruler and determine that I'm wrong, please be sure to let me know!