Getting old is something that we cannot avoid, no matter how strongly we wish. As we age, our skin starts losing its ability to renew naturally. Instead, the skin begins to lose moisture, grow thin and become loose. While, habits like smoking and drinking and certain diet related factors contribute to early ageing of skin, sunlight is known to play a vital role in skin damage and ageing.
It has been established through research and clinical studies that the use of sunscreen is the best possible way to prevent early wrinkles. it was found that people who used sunscreen daily were less likely to have wrinkles and dark spots after 4.5 years than those who did not. 
The formula of using a sunscreen is a bit complex. Everyone needs to understand the ‘how’ and ‘when’ of using it. However, it is always recommended that people should use a sun-block cream with other sun-protective measures and should apply it whenever they are going out or going swimming. It needs to be applied and reapplied every few hours while being exposed to the sun. One needs to look at the ingredients before using the cream/lotion. Some creams/lotions contain ingredients that block UV radiation exposure.
1. Organic creams contain UV filtering chemicals, such as octocrylene, octyl salicylate, homosalate, and octyl methoxycinnamate (block UVB), avobenzone-Parsol 1789 (blocks UVA), cinoxate, ethylhexyl p-methoxycinnamate (blocks UVB and small amounts of UVA), oxybenzone and benzophenone-3. As seen above, some of these help filter out both UVA and UVB light and help prevent early wrinkles. 
2. While sunscreen protects you from UVA and UVB rays, it also prevents sunburns and wrinkles. Sunscreens often contain SPF, highly effective at absorbing rays that cause cell tissue damage and lead to skin ageing. SPF 15 protects your skin from sunburns associated with exposure to UVB rays. For protection from UVA rays, one would need ingredients like avobenzone, sulisobenzone, titanium dioxide and zinc oxide. 
3. Sunscreen can help prevent photo-ageing. A study published in the Annals of Internal Medicine in 2013 has shown regular use of sunscreen can help prevent photo-ageing, i.e. premature ageing caused by the sun. For this study, researchers compared skin ageing in 900 men and women from Australia over an extended period of time. It was concluded that daily use of a sunscreen can reduce skin ageing including wrinkles, rough patches, sagging and discoloration by as much as 90%. 
. Study: Regular Sunscreen Use Can Prevent Wrinkles - SkinCancer.org. 2015. Study: Regular Sunscreen Use Can Prevent Wrinkles - SkinCancer.org. [ONLINE] Available at: http://www.skincancer.org/prevention/sun-protection/sunscreen/aging. [Accessed 01 October 2015].
. Seniors center: Skin wrinkles and blemishes . 2015. seniors center: Skin wrinkles and blemishes . [ONLINE] Available at: http://www.uihealthcare.org/ADAM/Seniors%20Center/10/000021.htm. [Accessed 01 October 2015].
. Understanding UVA and UVB - SkinCancer.org. 2015. Understanding UVA and UVB - SkinCancer.org. [ONLINE] Available at: http://www.skincancer.org/prevention/uva-and-uvb. [Accessed 01 October 2015].
. Mirror, Mirror, on the Wall - SkinCancer.org. 2015. Mirror, Mirror, on the Wall - SkinCancer.org. [ONLINE] Available at: http://www.skincancer.org/healthy-lifestyle/anti-aging/mirror-mirror [Accessed 01 October 2015].