I wash my very long hair 2-3 times a week and often get compliments from women. Many express some variation of "I wish my hair would grow that long" but none of them like the answer. "I do nothing to it. No heat treatments, no bleach, no color, no tight braids, no styling. Shampoo approximately every other day and condition weekly."
(Dish soap would probably strip the natural oils too aggressively, even for short hair. Rough on the scalp.)