This guide can direct you to resources that provide introductions to various topics in book history. As it stands, this guide appears to favor printed books in the West from the hand-press period (ca. 1450 - ca. 1830) -- largely ignoring, for example, manuscripts, machine-press books, and eastern traditions -- but this imbalance will improve over time.
While most of these resources are introductory in nature, many of them will point you in the direction of more specialized material. Read footnotes and bibliographies, and follow those trails.
Questions and recommendations are always welcome.