no one has control over the color of their eyes; thus, it’s not a very impactful compliment. However, someone may have made a very conscious choice to wear a specific hairstyle that takes an hour to get ready. If you compliment this, you are telling them you recognize and praise their effort. If you compliment their outfit, you are acknowledging their awesome taste. Other examples include specific habits, words and phrases people use, distinct fashion sense, unique thoughts, and so on.
