Leave-in Serum for FRIZZY TANGLED Hair. Ingredients: Bottled / Distilled Water. Regular water can also be used, though, it tends to turn bad in a few days. A clean spray bottle Extra Virgin Olive Oil- A Few drops Rosemary Essential Oil- A Few Drops. Mix every thing and shake very well. Spray on frizzy tangled hair before combing the hair. This DIY serum is great for de- tangling hair and avoiding split ends. Can be used as a leave-in serum after shampoo.