Marva Dawn
Reaching Out Without Dumbing Down and
A Royal Waste Of Time
Marva Dawn is an excellent place to start. "Reaching Out" is the one to start with, "Royal Waste" is her further thoughts and reflections from interacting with people over the ideas in her first book. You may think she is advocating traditional worship, but she tries to correct this misunderstanding in her second book.

John Frame
Worship in Spirit and Truth and
Contemporary Worship Music: A Biblical Defense
The first book is a good overview, in the second book he responds to many of the typical arguments against praise choruses. My main criticism of the second book is that many of the songs he holds up as good choruses are really kind of trite. He is a theologian and has a classical background and so he is not as familiar with what is excellent (musically) in the more popular musical genres. Still, very worthwhile reading.

Hughes Oliphant Old
Worship and
Themes And Variations For A Christian Doxology
Old is the leading scholar of traditional reformed worship, and he writes a column for Worship Leader magazine. He will help you appreciate the richness of the tradition. His dissertation, published as "The Patristic Roots Of Reformed Worship" (it's out of print and impossible to find except in libraries these days) proves that the reformers were really trying to go back to early church worship.

Terry Johnson (ed.)
Leading In Worship
This is an excellent resource that gathers gold from the best reformed liturgies and puts them all in one book! Great corporate prayers and wisdom on the order of a service too. High-Church in his perspective. You can learn a lot from this book.

Trinity Hymnal and Psalter
The Trinity Hymnal and
The Trinity Psalter
A good hymnal is invaluable. The Psalter puts all 150 Psalms in verse form and suggests tunes so that you can sing the Psalms in worship.

Louis Benson
The Hymnody Of The Christian Church and
Studies In Hymns
Both of these are out if print, but he is a great scholar of the history of hymns. Some of the modern hymn story books include apocryphal stories but his "Studies In Hymns" is reliable, and solid. I find his stuff through Internet sites like: abebooks.com and bibliofind.com

Henry Foote
Three Centuries Of American Hymnody
This is out of print too, but it is a great historical overview of hymnody in America. You will learn tons from this book! But beware, he is sympathetic to Unitarianism.

Asahel Nettleton
Village Hymns
This is a great 19th century reformed hymnal that has been reprinted recently. Nettleton was a famous reformed revival preacher (you should read his "Life and Labors" someday!)

William Gadsby
Gadsby's Hymns
This has been reprinted recently too. It is reformed Baptist and includes 1200 hymns (without music) and can be obtained (as can Nettleton's hymnal) from heritagebooks.org)

John Julian
Dictionary Of Hymnology
The standard reference work but it would cost you $100 if you can find it on the Internet used somewhere.