One of the things I get asked is the books that I use or recommend.  Tried to find the intersection of reasonable price, authenticity, simplicity,  availability, rich in visual aids and breadth of coverage. Below is the list. The general books are targeted at people who are starting and/or generalists.

General References:

Hindu Art by Richard Blurton 

Uses material from British Museum to develop the story. Great work with photos of exceptional items. The discussion and contextualization make one want to learn more. Covers the entire country. One of my favourites. Have read it twice so far.

Change and Continuity: Folk and Tribal Arts of India from Lowe Art Museum Univ of Miami. 

Excellent book with a large number of photos (300+). The photos and corresponding articles are grouped by region making it easier to focus on a particular region and/or see the regional differences.

South Indian Gods and Goddesses by H Krishna Sastri

Simply a must for anyone serious about collecting South Indian classical bronzes. The author has used primary sources to compile the book.  This book was published about 100 years ago and the quality of photographs reflect the technologies available then. Print-on-demand copies are available, as it is no longer copyright protected. The originals tend to be a bit more expensive. Scanned version is available in Archaeological Survey Of India site. This is one of my go-to books, especially for Brahmanical deities.

Studies in Tuluva History and Culture by Prof P Gururaja Bhatt

Covers Tulunadu history, Coastal Karnataka region including Udupi, Mangalore and Karkala belt. The documentation of deities in worship in temples and private residences will not be easy to replicate. I am yet to come across such comprehensive coverage for other regions. A real treasure trove of photos, over one thousand of them. The quality of photos reflects the technology that was available then. This book is now republished.

Iconography of Southern India by G Jouveau Dubreuil translated by A C Martin

Despite the title, the focus is on Tamil Nadu. One of the original works I have come across. This is based on authors personal research/experiences and primary sources. An underestimated work and highly recommended.

Iconographic Dictionary of the Indian Religions by Gosta Liebert

When in doubt I reach for this book. Excellent reference book. Based on extensive research of work by masters. Cross-reference to the source material makes it invaluable if one wants to learn more.