Ingredients:100g+ neutral henna (amount depends on length thickness of your hair)
1/2 an avocado
1 tsp oil of your choice (olive, grapeseed, castor, etc.)
1 tsp honey
1. Mix all the above ingredients together in a stainless steel bowl. (Assuming you are using pure henna, a stainless steel bowl should be fine.)
2. Section damp or dry hair. Apply using plastic gloves or an applicator brush, section by section.
3. Cover hair with a secure plastic cap.
4. Allow to set for a minimum of 4 hours. (Some ladies, henna overnight.)
5. Rinse hair thoroughly with warm water to remove henna.
6. Follow up with a conditioner wash.
7. Deep condition with a moisturizing conditioner for 20-30 minutes.
8. Rinse, moisturize, seal, and style as usual.
Source: Original recipe on LongHairCareForum