Inflammation is usually a contributor to skin issues, as others here have pointed out. Omega-3 fatty acids are powerful anti-inflammatories, so they promote healthier skin. They also have other health benefits including helping with anxiety and depression, and promoting brain health.
The best natural sources of omega-3s are fatty fish such as mackerel, salmon, cod, and sardines. If seafood doesn’t work for your dietary habits there are plenty of good omega-3 supplements to choose from.