First, flick through and have a look at the overall style of the drawings. Is this the kind of drawing you want to do? Some artists follow a classical atelier approach based on the live model, while some teach a more photo-realist style; others focus on expression, while still others are more suitable for cartoonists. Books from outside your genre may still be helpful, but you don't want to be fighting against your own aesthetics.
Secondly, consider the competency of the art and tuition. Artists can sometimes take on projects they struggle to deliver, and publishers sometimes don't know what readers want. I've seen some figure drawing books that were little more than a collection of sketches from bodybuilding magazines accompanied by the occasional note; not really much use to anyone. Reading through a sample of the book should quickly give you an idea whether you'll be able to follow and learn from the tutorial. Drawings should be clear and show the progression of the drawing.
Some people enjoy a lot of reading, while others just want examples. Books like Drawing on the Right Side of the Brain are terrific but more wordy, while Larry Blovits 'No Experience Required! - Sketching and Drawing' is an example of a great beginner's book packed with step-by-step illustrations that don't require so much reading.
I always take a look at negative reviews as well as the good ones - Amazon's website is useful for that - though I prefer to shop locally if I can. Sometimes what is a negative for another reader might be a minor hiccup for you or even a non-issue. If you are buying online and can't browse the book, try doing a web search for the author's name. It can be also useful to look for specific mediums - such as Colored Pencil Drawing Books and specific themes, such as drawing landscape, or drawing the figure.
More advanced artists can have a tough time finding something useful; you need to look for books aimed at Fine Art students or a specific aspect of drawing, such as A Foundation Course in Drawing, or Aristides' Classical Drawing Atelier. Also take a look at magazines: American Artist's 'Drawing' is a quarterly full of great content.
Do you have a favourite drawing book? I love my Bargue, but I still have a soft spot for the Walter T Foster classics that I grew up with - especially the ' Cats' book. I still have a sketch I copied from that book thirty years ago. I bought the 'revised' edition recently, a black-and-white revision of the original.