Once you've spent too much time in the sun without proper protection, simply avoiding more sun is not going to restore your normal skin texture or color. Neither is applying lotions and potions that barely penetrate the skin's outer layer, no matter how modern or advanced or expensive.
Most premature skin aging and almost all skin cancer is caused by sun exposure and tanning beds. The only safe tan is a fake tan from a jar, and even that means slathering industrial chemicals all over your skin.
The best way to protect your skin is to avoid direct contact with the sun. Short of staying indoors your whole life, that requires taking certain precautions.
Sunscreens are lotions, gels, or sprays that either reflect or absorb the ultraviolet radiation in sunlight to protect the skin from damage. Sunscreens come in a wide variety of formulations and strengths, noted as an SPF, or sun protection value, a very imperfect measure based on the time it takes to burn.
Most dermatologists recommend using a preparation with a SPF of 15 or greater, while at the same time stressing that there is really no safe level of UV exposure.
One important factor in determining the effectiveness of a sunscreen is ease of use. If it stings or is so greasy you can't stand it, most of it will end up inside of the tube rather than on your skin. Also, some of the more powerful sun blockers contain harsh chemicals that can be absorbed into the skin and possibly produce toxic side-effects.
Still, using less than the recommended amount of sunscreen is not a good idea. Several studies have suggested that most people apply only about 1/4 to 1/2 the amount they need to achieve the advertised sun protection factor.
Be aware that while ultraviolet type B (UVB) rays cause reddening or pain, ultraviolet type A (UVA) rays do not. UVA has been implicated as a major cause of malignant melanoma and skin aging, and yet some highly-rated sunscreens barely protect against this damaging wavelength (the ones that do often contain zinc oxide and look white when applied). So, since you can't judge protection by gauging how red your skin gets, it's wise to limit exposure to the day's strongest rays no matter how high a SPF rating your lotion may carry.
Of course, the only absolute way to avoid the sun's ultraviolet is to never go outside without a hat, sunglasses, full set of clothes, and maybe even an umbrella, which is hardly an enjoyable way to live your life.
• Update: Asian Americans getting too much sun