How to formulate skin care products with moisturizing & hydrating benefits?

There are 3 mechanisms in which moisturization & hydration elements work: 

1. Hygroscopicity: The ingredient has a great affinity for water, keeping it on the surface of the skin. It prevents transepidermal water loss (TEWL). Glycerine is an excellent example. 

2. Occlusivity: Ingredients cover all the pores by forming a layer and do not let the skin lose water. Keep TEWL limited. Vaseline is an example, but it is not so popular anymore. 

3. Tighter junctions: Gaps between the cells on the skin become tighter, so you lose less water. All isosteres can fit in this category.

A very demanding claim attached to moisturization and hydration is ‘without greasy feel’. It is important to note that nourishing agents contribute to greasiness as opposed to moisturizing and hydrating elements in your formulation.