I have had SD for 10 years, am now 30. I have it on my face and scalp and occasionally on my groin.
I wash my hair each day with Head and Shoulders antidruff shampoo and wash my face each day with E45 Emollient Wash. So long as I use these every day it will not typically flare up.
If I do dusty work (like DIY) it will usually flare up regardless and left alone will take a week for the shampoo and E45 to gain control again. So on my face I will use a thin layer of 1% hydrocortisone cream, twice a day for one-two days. That always clears it but is bad for the skin so is not a long term solution (you can end up with stretch marks).
I've tried lots of creams and moisturisers over the years but none have been as effective as the emollient wash.