For Hero Complex Gallery's 20th Anniversary Hellboy Show.
I detailed my process on my blog but below are also the steps I generally follow for every piece.
Step 1: Create Informal Subdivisions
Step 2: Look for image within grid and sketch
Step 3: Start building image in Illustrator
Step 4: Make sure final outlines match and follow logic/structure of grid
Step 5: Start building the shapes from the original outlines in grayscale to determine values
Step 6: Create color scheme
Step 7: Lay down colors