If you never read any of these, or if you tried the first one but bounced off the in-medias introduction, you should try Twenty Palaces. Ray Lilly got into trouble as a boy, got into more trouble as a young man, and then got into jail. Now he's out. He would like to avoid more trouble, please. His trouble-free period lasts about two hours.
The good news is, there's magic. The bad news is, I lied: magic is bad news. You can do magic the hard way, which hurts like hell and costs outrageously; or you can do it the easy way, by summoning demons that want to devour all life on the planet. I'd say "don't make a mistake if you choose the easy way," but it's pretty obvious what the mistake is there.
Anyhow, Ray attempts to free some of his friends from their mistakes. He runs into the inimitable Annalise Powliss, a hard-way sorcerer, who is also attempting to repair these mistakes -- scorched-earth style. Ray objects to this; unfortunately, it's hard to argue with Annalise's logic. Mostly because if you get in her way, she sets you on fire. Ray manages to avoid this, helps deal with the demon infestation, casts one (1) spell -- okay, two, but the second one is short-term -- and (spoiler) winds up as Annalise's "assistant". (No benefits, no salary, no life expectancy.) Thus we are set up for Child of Fire.
This is a pretty good book. The action is tense, the monsters are damn creepy, and the characters are reasonably interesting considering that they're just being introduced (and a lot of them wind up rapidly dead). If it were the first book I ran into, I'd say I'd try the next one and see if the series is solid. As it is, I can say that the series is solid; the books get stronger as you go (and we learn more about the characters and the setting). The prequel-plus-trilogy comes to a decent arc-conclusion, so you don't have to fear being left in mid-leap.
Yes, I am pushing this one. I would like people to read it, so that the author makes some money and continues writing and eventually strikes it rich and then comes back to the series. Sheesh his blog is depressing.