Can someone point me in the direction of a good trilogy or series?

Let me introduce you to the master of Science Fiction: Anne McCaffrey. If you have never read her books before I suggest you start with The Dragonriders of Pern series. The first book is called Dragonflight, then Dragonquest, then The White Dragon, and so on. They are so sosososososo good for any fantasy lover and if you don't absolutely love it by the third chapter I'd sign you into a mental institution! Read it!