Choose a simple source image with clear shapes and strong contrast
Open the image in an editor like Photoshop, GIMP, Aseprite, or Piskel
Resize the image to a small canvas size
Disable smoothing or interpolation when scaling down
Reduce the color count using posterize or indexed color mode
Manually clean up the shapes with a pencil tool
Use a limited palette of 8 to 32 colors
Add outlines where needed
Simplify details into readable blocks
Add shading with a few controlled color steps
Keep edges crisp and avoid soft gradients
Zoom in and refine individual pixels
Export the final image as PNG
Compare the result at 100% zoom and adjust if needed