The best advice: Buy by price. In a comparison of more than 30 moisturizers a few years ago, Consumer Reports found that the least expensiveplain old Vaseline Intensive Care Dry Skin formulaworked best. (It cost 28 cents an ounce, compared with $16 an ounce for the priciest moisturizer, which did less moisturizing than any of the other products tested.) You don't need different products for various body parts, though you may prefer a lighter formulation for your face.
You may find generics and store brands that you like. Comparing ingredients can be confusing, but you may notice that the pricey bottles contain pretty much the same stuff as the others. Whatever the product costs, the first ingredient is often water (which makes the product easy to apply), plus some form of petrolatum or oil, and/or glycerine. You may want to avoid perfumed products, since perfumes can be an irritant.
Other tips: Bathe in warm, not hot water, and avoid long showers or soaking in a hot bath, especially with bubble baths. Use a mild soap, and dilute it with water rather than lathering directly on the skin, since soap is drying. Bath oil may be helpful, if you bathe instead of shower. Avoid astringents. Apply moisturizer to slightly damp skin. Rubber gloves for household chores and warm gloves for outdoors can help keep your hands from drying out.