I just finished reading the quarter series by Tanya Huff. I am returning to school in a few days. I also work.

I wonder if there is a single volume that is a must read by her. I'd like to read more, but dare not a series right now. This was my second reading ot this series and I really enjoyed it.

Huff writes mostly series books.  I think there's only 2 or 3 non-series books plus some short story collections.

On the novels, there's Gate of Darkness, Circle of Light which I read about a year ago.  It was good but I wouldn't call it a must-read.

THe others are Fire's Stone and Enchantment Emporium (brand new, in HB only).  I haven't read either so I can't comment.

What you might look for though are the short story collections.  I found a copy of What Ho, Magic! last year and really enjoyed it.  She has a mage named Magdelene in a couple of the stories who is hillarious. 

I've never seen one of her works that wasn't part of a series. She also has a paranormal/horror/mystery series called Blood Ties. It revolves around a central cast of characters but the books are pretty much stand alone.

I would suggest reading one of her short story collections- What Ho Magic is good.  I wouldn't suggest the Blood series as stand alones myself, I think you need to read them in order to understand the dynamics at work between the main trio of  characters..IMHO :)