Washing hair (or water, generally) is terrible for dye; I am always so sad when I see that my dye has turned the water purply-red and it's all going down the drain, or seeing my dye in my hair towel. The simple solution was to obviously stop washing my hair as often. Although my hair doesn't get oily as quickly as it does for other people, washing my hair only once a week meant some greasiness was inevitable.
The other downside is that if my hair gets really oily, No Drought is not as effective as an aerosol dry shampoo. I've applied No Drought to refresh my hair and gone to work, only to realize that my hair quickly became greasy-looking again in a few hours--this is when I know it's time to bust out the aerosol stuff.
I apply No Drought directly to my hair by holding the bottle low over my head and squeezing it, distributing the powder in small "puffs" all over the crown of my head, then massaging it in. I've tried other methods too, like rubbing it between my hands and then massaging in (kinda messy?), and putting the powder on a boar bristle brush and brushing my hair with it (not as effective).
Overall, I really like No Drought and would definitely buy it when I run out. Although the bottle may look small in comparison to a big can of aerosol dry shampoo, it's the better value because this small bottle lasts longer. It works for me because my hair doesn't really get super oily even after a week of no-washing, but I would skip if very greasy hair is a problem for you. It's also messier to use, so you're better off with a small aerosol can if you're the type that needs to refresh their hair outside of home.
Available at LUSH: $14.95 CAD / 130 g (pictured); $7.95 CAD / 55 g
Ingredients: corn flour (Zea mays), magnesium carbonate, talc, fragrance, grapefruit oil (Citrus paradisi), lime oil (Citrus aurantifolia), citral, geraniol, limonene, linalool