Unless you understand book printing, you should let a designer or print buyer coordinate the printing for you. Book printing is specific with regard to sizes, page count, inks, photos, prepress, etc. Of course, you could spend a lot of time receiving an education about print from printers and salesmen and design a book that is printable. This book covers every technical aspect of the industry. The following book sizes will cut your printing costs dramatically.
Printers buy paper in bulk at certain sizes.
Page size is contingent on the most economical fit for the paper that can also be accommodated on press. You can print a size different from those listed but it will cost extra for prepress and press adjustments. These sizes are categorized according to their most common markets. The negative, or film, of that signature is transferred to photosensitive paper, called bluelines, which are used to give you a dummy of your book for final approval. The cover is also color-separated and recomposited as a proof for your approval.