One tip I tried that slightly helped after many years of suffering is....dont use hot water on your head. Seems so simple right? I love hot showers. So hot. But I'd never put my face under that hot water because I know it'd damage my skin. I didn't realize that the skin on my head might be drying out and suffering from the hot water. This also helps if you have back acne.

One of the only things that completely (and temporarily) solved my lifelong dandruff was Accutane. It was a great 6 months. And then it slowly came back after I stopped taking it, so honestly at this point I've just accepted I'll always have a little bit. Tea trea oil and dandruff shampoos make my dandruff so much worse.