I've been working in libraries for a little over three years and  while I really enjoy leading Storytime programs, I'm still learning what  works and what doesn't. This blog is mainly going to focus not so much  on songs, activities and crafts (although I'm sure I'll address those  topics from time to time), but on books.
At our branch,  most of our Storytime audiences are on the young side,  generally young  preschool. We can have anywhere from 20 to 60+ children  (not counting  adults) at each program, so it's important to have books  that are  easily visible and will hold their attention.   
I plan to evaluate each book on a scale of 1-5 (1 = lowest, 5 = highest) in the following areas:
Storytelling
Color Attractiveness
Size of Book
Text Size
Illustrations 
Participation Potential
Overall Appropriateness for Storytime