There are different recipes, depending on the ingredients that are available, I use a lot of Aloe Vera, mint or cayenne leaves (fresh), glycerin soap. lemon juice, almond oil or coconut (if you have dry hair), as you mention lavender essential oil will allow you to create a relaxing homemade shampoo with a delicious fragrance. I leave a tip, a ripe avocado alone or mixed with an egg serves as an excellent cream bath, leave your hair soft, shiny and strong.