Start chugging good old H2O. Your skin cells are mostly water, similar to other cells in your body. When you aren't hydrated enough, your skin literally shrivels -- think of a raisin versus a grape. The result is a higher rate of skin cell turnover (death) that makes the skin of your legs and other body parts look dull, as well as fine lines that make your skin feel rougher.
Scope out the ingredient lists on all of your hygiene and skin care products such as soaps, shampoos and body washes. Say goodbye to ones that have ultra-drying ingredients -- these tend to be any ingredient that ends with "ate" or "ben," with perhaps the most notorious agent being sodium laureth sulfate, a detergent that makes suds. In general, if you can't pronounce it or haven't heard of it, the ingredient likely isn't good for your skin. Replace them with natural, herbal-based products that don't have any added chemicals, dyes or perfumes that can irritate your skin. Ingredients such as shea butter, olive oil, chamomile and aloe all are good options.
Make like a bunny and nibble your veggies and fruits. Toss in foods such as nuts and salmon, too. Fruits and veggies are loaded with minerals and vitamins that are awesome for skin such as vitamins E and A, and they also have antioxidants and alpha hydroxy acids that help prevent cell damage and encourage healthy growth. The omega fatty acids play key roles in skin cell function and are required for strong cell membranes.
Exfoliate your legs once or twice a week to take off yucky dead cells and residue -- more often can irritate your skin. The simplest exfoliation method is just to gently rub your legs with a washcloth while you're in the bath or shower. Exfoliating gloves also work, as do sugar scrubs. You also could make like Cleopatra and wash your legs with milk. Milk has lactic acid, an alpha hydroxy acid that is a mild exfoliator.
Apply a water-based moisturizing lotion whenever you feel like your skin is a little dry or you know you'll be in a dry environment. Once that soaks in, follow up with a good natural oil-based lotion such as those with shea butter. Oil-based lotions don't really moisturize well, but they seal in the moisture already in the skin and create a thin barrier that keeps the environment from stealing water away. They help your skin look smooth and healthily shiny to boot.
Find lotions that naturally contain alpha hydroxy and beta hydroxy acids. Both exfoliate from the chemical perspective, so when you go to wash later, it's easier to get rid of dead skin cells and excess oil on the skin. Use more beta hydroxy acids if your skin is oily or acne-prone, as BHAs penetrate deeper and are antibacterial and anti-inflammatory.