That's a tricky one, there's no easy remedy. They're called nasolabial folds and they're a normal female problem. It depends on your budget, the most expensive is surgery in which a surgeon will tighten them up, the next cheapest choice is Botox or a filler of some description. A good dermatologist can help you with that (make sure of their qualifications). If they're both to steep for you, I'm afraid it's down to good old skin care. Buy a skin cream with vitamin A or retinol in it and over time it should help. To be honest we should all do this anyway, remember the three steps cleanse, exfoliate and moisturise. And always wear a moisturiser with sun cream of SPF30 or more.
Most of the semi expensive stuff is not better than a nicer perfumed version of the cheaper stuff. I'm afraid paying a bit more is key here.
Hope this helps.
Siobhan.