There are loads of books out there on composition in painting (and photography too). All of them contain the same information, but present that information in different ways.
Of all the books I own that contain artistic composition chapters, the one called “Classical Painting Atelier” by Juliette Aristides, is one of my favorites.
Everyone knows what the “rule of thirds” is in pictorial composition, but in Ms. Aristides book, the idea is covered in much greater, and more interesting detail. She Explains and illustrates the “armature of the rectangle”, which is essentially a way to divide the picture plane and place subject matter in a way that will give you an effective, and pleasing composition.
Reading the book, you learn where this harmonic division of space originated, and you see various examples of how great artists have been using this armature for centuries to create their masterpieces (it goes all the way back to music and early Greek civilization folks). The Greeks rocked at artistic composition!
Circles indicate division of horizontal and vertical thirds.
The book also goes into detail on how that armature has been adapted to picture planes that are not typical rectangles - like altarpieces in a church, or decorative shields (works in tondo) for instance.
The cool thing is, you can take any of your favorite paintings from history, and apply the same divisional lines to them, and learn a bit of the compositional thought process and design decisions made by the artist. This is stuff that makes the viewing experience that much richer!
Ms. Aristides is a super oil painter, and her book is beautiful and informative!
When not working from life, I work from my own photographic source material. The composition chapter in “Classical Painting Atelier” struck me so hard that, shortly after reading it, I catalogued all of the various sizes of canvas and supports I own, then went into Photoshop and created the armature for each size, which I use during the planning stages of my painting process.
Now when I review reference photos I shoot, I can design and crop them properly, not only putting the center of interest where it should be, but manipulating the secondary parts as well, in a fun effort to come up with the best composition I can.