STefan...your aiight, 18 and three dates aint nuthin unusual, ive had friends who started dating at 9 and some at 21, we're all different...soem good suggestions have been given: ask her about herself, find out what she likes, have her talk about herslef,,(unless shes really shy at first this will get things started)
if she truly is hot give it another shot..talk somemore b4 u go out again and do something she likes, not a "safe" thing like movie, pool, etc..maybe she like horseback riding =) no really though, then you have something to talk about all day: how the ride was, how many times shes been riding, etc... well maybe im thinking other things but hey all that talk about riding cant be bad....
or get the Free Nissan picnick backpack in Hot Deals forum and take her out on to a lunch in the park...