I try to do the Khadgamala Stotram regularly and of late I have been fascinated with how the different Khadgamala Devis are placed on the Sri Chakra and the reasoning behind it. This lead me to two books on an introduction to Sri Vidya tradition. Both are not easy reads, infact they are heavy and sometimes too overwhelming. But it is a treasure trove for the really interested beginner Sri Vidya upasaka.
Also some of the excellent sources for more information are:
Sri RajaRajeshwari Temple, Rush, NY (which I visited recently, but more about that in another blog post)