Take five large tablespoons of Reetha in a litre of water, boil it until water reduces to half. Strain the Reetha out using a sieve or a piece of cloth, use the liquid as shampoo, body wash, hand wash etc. Increase or decrease amount of Reetha according to hair length. You can store the excess in the fridge.
Wet hair, apply Reetha liquid all over scalp & hair, massage to create lather, leave on for a few minutes, rinse off with plain water. Do not shampoo.
Or, soak Reetha in a cup of hot water according to hair length or body wash; leave for a few hours and then use directly with out straining. It will also work as a mild liquid body scrub.
Or, make a paste of Reetha powder with warm water, apply all over scalp and hair, massage to create lather, leave on for a few minutes and rinse off.
A paste of Amla, Reetha & Shikakai can be applied all over hair and scalp, massage to make lather, leave on for a few minutes, rinse off. This works as a natural hair wash and hair conditioner at the same time. Reetha cleans, Amla gives gloss & shine and Shikakai conditions making hair soft & manageable.
Or you can boil all three in equal amounts and use the decoction to wash hair. Use a glass container to boil.
Take care to see that Reetha does not enter eyes. Rinse off immediately.