I'm too new at this to recommend many books, but I have to say that so far, Teach Like a Champion by Doug Lemov has been the most helpful for me. I don't have any formal training as a teacher, and this book helped me understand why the techniques I've accidentally discovered while teaching before work, and it gave me practical tips that I can actually use. I don't need philosophies, I need tools. And this book provides tools. It comes with a DVD so that you can see some of the techniques in use in a classroom. This is a book intended for public school teachers, and not every word is applicable to Seminary, but the vast majority of ideas will help you. I bought mine at Amazon, but you may find it cheaper at http://www.half.com/.
My friends who teach Seminary suggested the following books to me, and I am passing along those titles to you:
The Made Easier series
DeAnn recommends that The "Made Easier" series by David J Ridges. She says she uses these books alongside her manual and scriptures when reading the scripture block to help her understand passages better. There are several of these books out there:
Brent suggested New Testament Apostles Testify of Christ: A Guide for Acts Through Revelation by Kelly Ogden and Andrew Skinner. At this writing, this book seems to be out of print, but it is available very inexpensively used.
Stop Struggling, Start Teaching - This is my favorite of the LDS teaching books. It is the only book that really has a list of help for teachers trying to help disruptive students. I was surprised at the quality of the help.
Becoming a Great Gospel Teacher: Bringing the Gospel Classroom to Life was recommended by DeAnn and sounds like a book much like Teach Like a Champion in that it is full of practical gospel teaching advice in a Q&A format.
Do you use a great book to help with your teaching? Please tell me about it below!