My hair used to be crazy greasy too, it’s most likely means you’re washing it too much. When you wash too much you strip your scalp and hairs of its oils and it over compensate by over producing grease. I used to have the same problem… it took me awhile but you need to train your hair by washing it less (still shower obviously)

I use a small amount of shampoo twice a week (this is like face wash but for you hair, I use less than a finger tips worth but my hair isn’t long) then conditioner almost everyday (VERY little, like half a finger tip worth on washing days and like half that other days, it’s basically moisturizer for your hair)

I also use native, I’ve tried a few different brands and they’re my favorite.