How do you do your skincare at home?

I’ve tried doing a face mask every day, sleeping with a generous amount of cream, and washing my face thoroughly. However, the occasional acne breakouts and skin troubles, especially the allergic reactions to sunscreen that flare up when the sun is strong, are really worrying me. It subsided after taking antihistamines, but... how should I soothe my skin when it swells up and itches? I’m really curious about how to calm my skin. Diet and daily routines must be important too, right?