I just read Primary Inversion, and while I'm on the hunt for more of Ms. Asaro's books, I thought I'd ask... Do her books have to be read in order?

When I read through her website it looked like quite a few books in the Skolian Empire series revolve around various characters, so I assumed they don't have to be, but I'd rather be sure, before I start another of her books!

Also are all her books written with first person narration?

thanks for any help :)

Several of her books are stand alones.  The Veiled Web.  The Phoenix Code.

There is a group of fantasy books from Luna, the Charmed Sphere / Misted Cliffs. 

Then there is at least three groups that are interconnected within the larger Skolian series.  The Lask Hawk and The Ruby Dice.  Another one with all the Key books.  And Soz and her children's books.  While some of them are fine alone, I'd recommend in order.  But what order?  I have no idea.  The politics gets complicated and refers to previous books.  And at least one character is named after another.  She usually has a family tree and time line in the back.  Her Skolian series is a multi generational family saga.  And if I remember correctly, the time order and the publishing order don't line up.  The books don't have a clear numbered order.  The Last Hawk was published third, but is one of the earlier ones in the time line. 

as it happens, i read the newest Skolian Empire book tonight so i've been thinking about this question.  a lot of them will be much better read in order, but the order itself is a little fuzzy since published order and chronological order are not at all related.  you can see both published order, and chronological order at the wiki page, but it doesn't have the years specified: http://en.wikipedia.org/wiki/Catherine_Asaro

here's the timeline tucked in the back of Diamond Star, just the lines for the novels:

• 2203 Skyfall - Roca & Eldrinson
• 2227 Schism - Soz
• 2228 The Final Key - Soz & rest of family
• 2258 The Last Hawk - Kelric
• 2259 Primary Inversion - Soz & Jabriol
• 2259 The Radiant Seas - Soz & Jabriol
• 2277-8 Ascendant Sun - Kelric ; The Quantum Rose - Vyrl & Kamoj ; Spherical Harmonic - Deyha  ; The Moon's Shadow - Jabriol III
• 2287 The Ruby Dice - Kelric & Jabriol III
• 2328 Catch the Lightning - Althor & Tina

Diamond Star is not listed, but from some other things i believe chronologically it's right around 2279.  it definitely goes after The Moon's Shadow.

so, in general try to read the groups together, and read the ones with the same main characters in either chronological or published order.  Catch the Lightning i think can get read whenever.  Primary Inversion, The Radiant Seas, and The Last Hawk should all be read before the group of four that all take place in 2277-78, which i think i have in the right order (but Hawk is ok either before or after Seas).  The Ruby Dice must be read after the group of four, as does Diamond Star, but i don't think it matters which of those gets read first.  Schism & The Final Key should be read together, and those two plus Skyfall should probably be read before Diamond Star to get the full family background, but i *think* are probably ok to read anytime after Primary Inversion (they were published after The Moon's Shadow).

Also are all her books written with first person narration?

no.  i know for sure the one i have on hand isn't, and i don't think many were.  doing a quick peek, it looks like Primary Inversion and Catch the Lightning are, but probably not the rest.

So which book would you recommend for someone beginning this series?  A book that's gonna grab my interest and make me want to read the whole shabang?

for a new person, i would definitely start with the first one published - Primary Inversion.

Yes, I would agree with that, but then switch back to the chronological order.  I read one that was late in the series and spent a large part of the book trying to put things together that didn't go...  The book was good, but the connections I was trying to make were distracting.