Well I don't know how serious your relationship is, but you can't go wrong taking her out on a dinner
taking out for a dinner is an old style..... you will see about 90% of the world will do the same thing so bring some uniqueness in your personality and do something differ from others
I love the idea of giving/ getting experiences. Something you can do together that will create a memory long after the flowers die and the candy is eaten. Concert tickets, trips (even day trips), and planned events are great!
A dozen premium red roses is a classic Valentines Day gift that is great on its own or combined with gourmet sweets.