Mix one teaspoon honey and one teaspoon baking soda, until the mixture become a paste. Honey can moisturize lip skin.
Use the mixture to gently rub the lips, and after a few minutes, use lukewarm water to wash off. Then wait until the lips are not wet. If you are not using a lip balm, you can use some olive oil to moisturize. You can also use unsalted butter, as butter has the similar effect. This home-made solution can help to improve lip skin texture.
If there are mouth corner cracks, it usually indicates a deficiency of Vitamin B2. You will need to take vitamins supplements.