When sourcing POD books, you must prioritize paper weight (GSM), binding type, and printing technology. For interior pages, 80-100 GSM offset paper is standard for text-heavy books, while 120-150 GSM coated paper is better for image-rich content. Binding options such as Perfect Bound (glue), Saddle Stitch, or Hardcover (Casebound) should be selected based on the book's page count and target market. Ensure the supplier uses high-resolution digital inkjet or toner presses (at least 600 DPI) to maintain text sharpness and color accuracy.