Cream Caramel
Its the manga that got me into Shoujo manga.

" I might be cold, but I do have emotion "

Fruits Basket - I actually saw the anime first (I don't remember if it was the first shoujo anime I watched, though). I probably share this with many others as a first shoujo.

Most of the early manga I read was not shoujo, because it don't usually like "girly" stuff when it comes to Western fiction. I read a lot of shounen (which I didn't really like) before finding out that I liked shoujo and josei more.

The first shoujo manga I got addicted to would probably be "Absolute Boyfriend." xD But geeze, do I regret that being my first manga though (won't spoil anything, but anyone who's read it will know why). I guess you could say "Fruit's Basket" was my first. But I never read it, only watched that one. :-P