Best only as rinse out. I think using as leave in or gel may irritate your scalp.
I wash with Trader Joe's Tea Tree Tingle, RO with Tresemme Naturals, and use either SheaMoisture Milk or KCKT as a leave-in, depending on what I think my hair needs. KCKT isn't really a very moisturizing leave-in, but generally I don't need much extra moisture. I could get away with just using Tresemme for everything, but I think I get better results using different products.