Gather distilled water
Add a primary surfactant such as sodium lauryl sulfate or sodium laureth sulfate
Add a secondary surfactant such as cocamidopropyl betaine
Add a thickener such as salt, xanthan gum, or hydroxyethylcellulose
Add a conditioner such as polyquaternium or panthenol
Add a preservative suitable for water-based products
Add fragrance or essential oil if desired
Add a chelating agent such as disodium EDTA if desired
Mix ingredients until uniform
Adjust pH to about 5 to 6
Test and adjust viscosity
Fill into clean bottles
Store in a cool, dry place