|Cryptozoology, BioForteana, Zoological Oddities, Unusual Natural History|
The Finished Product
The most widely used POD printer is Lightning Source, Inc., so I will use their books in this discussion as the "typical" POD example. (Most subsidy and general POD publishers create the digital files in-house, and upload them to LSI's site, where the actual printing takes place. The only large competitor to LSI is Amazon's BookSurge/CreateSpace program.)
Most books are printed in 6"x9" size, but there are several available sizes. 6x9 and smaller will have a thicker, slightly tinted paper, while larger sizes' paper are a little thinner and bright white. Larger sizes are particularly nice for black and white sketches.
The standard books are printed in black and white only, inside. Because of the nature of the printing (think big laser printers), photographs are very tricky. I strongly suggest not using photos internally unless absolutely necessary.
Instead, photos and color images should be relegated to the cover, and often look quite good on the back cover. Covers are printed at 300dpi CMYK, so photos come out pretty well, although colors can shift a little due to the RGB to CMYK switch (you really can't determine the correct colors by looking at your computer screen, which shows RGB).
Now, I'm not a graphics designer, so most of my early covers were fairly lousy, but with a little research and practice, you can put out a decent-looking cover with Photoshop. Keep the Title and Author's Name on the front large, use appropriate fonts (no Times New Roman), and keep small text to a minimum. Because LSI covers are rasterized prior to printing, small text does show some fuzziness at the edges.
Obviously, text quality will be determined by how well it is written, and whether it is necessary to have someone edit it. When in doubt, have someone edit. (By all means, have someone factcheck, as well; I've found it helpful in several cases to have other investigators read through a book before it was published.)