Michelangelo is said to have remarked that when sculpting marble, he viewed as a matter of simply freeing the image he saw from the stone.
I feel similarly when I'm approaching my 2D work. Whether it's a panel of wood, a scrap of mat board, or a piece of watercolor paper, there is something subliminal leaking out, in several layers of discovery.
It may surprise many, but I rarely have a definitive plan for what I'm going to do when I sit down at my desk to make art. Instead, I keep a running list of ideas: my "stock" arsenal of creatures and concepts, new inspirations, suggestions, and anything else that runs across my brain. And then I consider the potential of the "canvases" before me.
My wooden panels are cut down from a single larger sheet - which is carefully selected for its grain, texture, and overall "feel." I'm sure I confuse the heck out of the hardware store staff as I'm pulling out sheet after sheet (most as big as I am, or bigger), and looking over each sheet, front and back. (I always put them back after I've chosen the winner.) Then after they are cut down, I select which side to gesso (paint primer). Depending on how many layers of gesso I use, the grain may still be slightly visible or totally obliterated - so even the coolest grain patterns get hidden.
My "tiny originals" are rescued mat drop-outs. (When you cut a picture mat, the drop-out is the beveled center left from the newly created picture window). Picture framers are notorious for saving mat board, especially if it's still big enough to be re-cut - because good mat board is expensive and it's important to both minimize waste and save money. These pieces, at 3.125"x 4.625" were too tiny to be machine cut into anything else, but they were so damn cute (and acid-free) that I collected them. They don't need to be prepped like the wood panels do, but whenever I have leftover acrylic paint that is going to go to waste, I wash it over the faces of these little mat boards to give them an interesting surface.
Anyway, so when I sit down to make some work, I have a small pile of prepped panels in front of me. And I carefully go through each of them and see what they "say" to me. I wouldn't compare it to trying to figure out what shape or image an inkblot or cloud is, as "asking" them what they want to be. If I do have a general idea I want to paint (like an owl, or a custom portrait) it's a similar process - which panel works best? Is that the face of a cat peeking out at me? A swish of a tail or the shape of wings in flight? Then I work to bring that image to the surface.