Skin care in your 30's?

Hey there
All throughout my 20's i've used a mild cleanser and an spf 15 everyday (Dove – as I have sensitive skin). It's been working great but now that I'm in my 30's I was wondering if I should change or do anything to my regime for preventative measures (fine lines etc).

I'm afraid if I go to the beauty counter at the department store they'll try to talk me into 100 dollars worth of stuff I don't need LOL