Librarians appreciate the contribution small press titles make to the overall quality of a library's collection. They like quality books that are bound well enough to withstand the multiple circulation the book will have. A quality cover and a well constructed, informative index. Kirkus Reviews 200 Park Ave. They like to get your book in advance.
Most librarians treat direct mail one notch above junk mail.
Most go through it and toss it rather than make a decision right then. The title has to really get their attention for it not to go directly in the circular file. Never just drop in on a librarian. Make an appointment and be prompt. If you send direct mail be sure to attach any reviews the book has received.