How often you should shower usually depends on your age. Older people, babies and young children are more prone to dry skin, which can lead to eczema, so bathing every other day is best. For most people who have relatively normal skin, bathing every day is OK, but there are things you can do to avoid it drying out.
Skin hydration is ensured by the bricks-and-mortar structure of the dead skin cells on the surface, which are bound together by natural moisturising compounds such as ceramides. Together, they keep moisture in your skin and prevent it from evaporating, but frequent bathing can strip this barrier away.
To protect it, avoid taking scalding-hot and very long showers. After showering, apply moisturising cream while your skin is still damp, to lock in that moisture, rather than drying yourself thoroughly and then applying cream. If you have sensitive skin, avoid heavily fragranced soaps, which contain additives that can cause irritation or allergic reactions. Choose brands formulated for your skin type.
You do not need to wash all over unless you are really dirty; soapy water will run down your legs and feet anyway. But the upper leg and groin area is one to wash regularly, because it can become colonised by pathogens.
People often want to scrub their skin clean, but most exfoliating scrub products can cause traumatic micro-abrasions on the skin. In general, if you want to exfoliate, acid-based accelerators, such as glycolic or lactic acids, are more gentle. When it comes to your feet, products containing urea, which breaks up dry, dead skin cells, will soften better than abrasive scrubs.