ooh! what fun!
I say hit the Guerlain counter and smell 3 of their finest:
Vol de Nuit
All 3 have lots of reviews here in the Basenotes directory, so take a look and see if you like the sound of any of them.
I don't know how you feel about heliotrope as a note in fragrances (it seems to be love it or hate it) and if you don't know what it smells like, don't worry. It's in L'Heure Blue, which smells a little bit sad and strange but absolutely beautiful. That perfume was my introduction to the world of perfume outside what I'd seen in department stores or magazine adverts.
And you can get a decant of scent to try it out on your skin over a period of time without shelling out for a full bottle. If you get post from the USA take a look at http://www.perfumeposse.com or http://theperfumedcourt.com as they sell decants and have a good reputation as honest upstanding traders.
The only thing is that as you learn more, you want more perfumes. You hear about something that sounds delicious and go miles out of your way to visit a shop where you can try it. Ah well; no calories at least.