Use consistent lighting, framing and a neutral background. The aim is to make differences between products visible rather than amplify them through editing.
Keep the setup fixed
Photograph the swatches at the same distance and angle. Avoid changing exposure or applying different colour filters between comparisons.
Record the conditions
Save the product code, base and number of layers with the photograph when known. For reflective finishes, add another angle instead of treating one view as the whole effect.