There are so many henna recipes with so many different combinations of various items that first-time henna users can be paralyzed or overwhelmed. Here is a basic recipe that comes from an Indian website:
Ingredients:
Henna powder, 2 cups (about 200 grams)
Warm water, 1 cup
Lime (or lemon) juice, 1 teaspoon.
Simple, huh? Well, this is a basic, no-frills, how-they-did-it-back-in-the-day recipe. This is pretty much the recipe I use when I'm in a "get 'er done" mood and don't feel like being creative.
Stir the ingredients into a thick paste. The acidity of the lime or lemon juice and the warmth of the water help release the colour. Let it stand for at least one hour before application.
The site does recommend additives for those who want to get fancy such as ground cloves, coffee, amla powder. It even suggests mixing henna "in an iron vessel" to help give a dark brown shade. I'm not vouching for that one (but I've read it on more than one Indian website), but I do know that you can mix henna in any type of bowl - plastic (will leave stains), glass or metal. Think of mixing flour.
The site also suggests that for dry hair add an egg and a tablespoon of coconut oil/olive oil/mustard oil to your henna mixture. I can say I've added egg and olive oil to my mix on different occasions. The egg is suppose to make your hair shiny but it's hard to tell because my hair is so shiny from the Vatika Oil I use. However, I've stopped adding any kind of oil to my mix because it may keep the henna from fully coating and binding to the hair.
Lots of people like to leave their henna on for HOURS but this totally unnecessary. Most authorities say from two to four hours. I know I have to keep it on for at least 3 hours because of my white.
Anyway, I'll be posting other recipes or at least links to them.