Tamora Pierce was a queen in my friends' and my eyes when we were in high school! We obsessed over every new book and read them multiple times. We shipped characters before "shipping" was a term. We learned that females could be protagonists, strong individuals, and stand up for themselves in a man's world. And yet they didn't all have to look the same. Female characters can be just as varied in opinion and action as we ladies are in the real world. From Alanna, Daine, Kel, and Aly, we learned all about GIRL POWER!
So Tammy has written a lot of books. Essentially, there are two realms that she writes in: The Tortall Universe and The Circle Universe. They aren't related, so you can read just one or the other.
Within each universe series, there are sub-series. You can read the sub-series as stand-alone series or you can read them all like one big series. Here is the chronological order for the Tortall series, since we have them all.
Beka Cooper: A Tortall Legend (Beka)
[Set 200 years before The Song of the Lioness quartet.]
The Song of the Lioness (Alanna)
1) Alanna: The First Adventure
2) In the Hand of the Goddess
3) The Woman Who Rides Like a Man
4) Lioness Rampant
The Numair Chronicles (Numair)
1) Tempests and Slaughter
Tammy's newest sub-series, so the first one is the only one currently out!
The Immortals (Daine)
1) Wild Magic
3) Emperor Mage
4) The Realms of the Gods (fav!)
The Protector of the Small (Kel)
1) First Test
3) Squire (absolute fav!)
4) Lady Knight
1) Trickster's Choice (fav!)
2) Trickster's Queen (fav!)
Go forth, readers, and partake of a monumental series!