Choosing hair color when palettes disagree

[Ameliasn]

I am trying to work out my undertone before choosing a few new clothes, but the phone camera gives me a different answer almost every time. Under a warm bulb my face looks golden; by the window it looks cooler. The mirror seems more consistent, though I know nearby walls and clothing can cast color too. I am hoping to make one repeatable comparison rather than collect more screenshots. My plan is to use indirect daylight, remove makeup, keep the same camera settings, and hold two fabrics close to my face in the same place. I would look for changes in redness, shadows, and how clear my eyes appear. Is that a fair way to compare? I am especially unsure whether a plain white background helps or simply makes the phone adjust its exposure again. If I take pictures, I would also keep the reference fabric in each frame so I can compare them later. I looked through an explanation of skin tone analysis while learning the vocabulary, but I would rather check the conditions of the test than trust a single label from an image. If you have compared fabrics yourself, which steps made the difference easiest to see? I am happy to run the comparison twice. I am not looking for a perfect camera score. I can record the time and lighting for each photo. I would welcome specific advice.