Liquid soap by the hot process method is a lot of work, and not a good project for a beginning soapmaker.
Making bar soap by the cold process method is easy, and olive oil soap is a great beginning project.
Traditionally, for many soapmakers true Castile soap is made with 100% olive oil. However, the name "Castile soap" is given to other soaps. Here is a blog about the name and the controversy over its use:
Here are instructions for cold process, olive oil, bar soap:
I make the bars and then dissolve them in distilled water for shampoo and shower. Adding a little castor oil to the recipe gives bubbles in the lather. Olive oil soap does not lather. It just feels sort of slippery.
I use it with baking soda for brushing teeth, too.
I have found that I feel better using only soap, not detergents. Most commercial shampoos, soaps, etc., even at health food stores have surfactants, and are not true soap.
Info on detergents and surfactants:
Detergent surfactants were developed in response to a shortage of animal and vegetable fats and oils during World War I and World War II. In addition, a substance that was resistant to hard water was needed to make cleaning more effective. At that time, petroleum was found to be a plentiful source for the manufacture of these surfactants. Today, detergent surfactants are made from a variety of petrochemicals (derived from petroleum) and/or oleochemicals (derived from fats and oils).
[I added bold type.]
Info on soap here:
Soaps are water-soluble sodium or potassium salts of fatty acids. Soaps are made from fats and oils, or their fatty acids, by treating them chemically with a strong alkali.
If you've ever put some salt in a greasy pan to wipe out the grease, you've made a mild form of soap.
Making cold process soap is easy, but there are safety precautions which must be followed. Proper preparation and tools/ingredients, and knowing exactly what one is doing are absolutely necessary for safety, due to lye being extremely caustic.
For me, real soap is as much a part of health as a good food plan.