For all you teenage singers out there, I can't emphasize enough how good Bach and especially Handel are for a young voice. Singing this repertoire requires vocal agility, great breath control and stamina which are all essential skills to acquire if you want to be a good singer.
Technique aside, this will also introduce you to, if you don't already know, some fantastic repertoire. The oratorios of Handel and Bach are some of the most widely performed pieces in the choral repertoire so learn them now and you will use them for the rest of your career.