Eat healthier foods? Drink more water, exercise, get good rest.
Don't keep drinking alcohol, eat fatty foods, cut out the sugary stuff, the processed foods.
I would have to disagree, respectfully. Our appearance is usually different from the way we perceive ourselves. Because negative feelings lie. We feel insecure for no reason and on the flip side some people don't look that great but perceive themselves to look really good. Personal experience with this: Before when I was struggling with low emotions I had the belief that I was "ugly" even though others would say I was good looking. It was a stupid, nonsensical belief and perception I would see in the mirror that had no baring in reality. But that's how negative feelings lie, and cause body dysmorphia. And yes, projecting those feelings didn't make me look better, while projecting feelings of looking good, does improve your looks.
Specific advice for Cleo: You're just noticing your flaws while other people notice your strengths, or other endearing things. Just give yourself more love, and also take practical steps be it exercise, healthy eating etc. But I'm pretty sure this is mostly in your perception.