This tip is only to be used in a pinch, such as when you want to apply sunblock or you just need to look great for a photo. Ice will shrink your pores and thus prevent sunblock from entering. The effect will last anywhere from a few seconds to a few minutes.
Of course, you can’t use this technique all of the time and you need to ensure you aren’t creating blockages by using it when you are sweaty, after you have applied makeup, etc.
If the above tips don’t do much for you or you feel you need a little professional help, then consider consulting with a dermatologist. They can offer treatments that exfoliate the skin with chemicals and with light, both of which are highly effective. Professional treatment can be expensive, however, so see if the remedies above work for you first.