"Iteration is about continual experimentation based on user feedback."
- IDEO, Design Thinking for Libraries
Congratulations... on starting what will be an ongoing, ever-evolving process! User experience design is never really and truly done - especially for libraries, where patron priorities and service needs are always changing. If you want to carry on with UX in the long run, be ready to continually observe interactions and invite feedback to keep making improvements wherever necessary.
Failure is essential. In order to get the best results, you have to push beyond boundaries. Willingness to fail and learn and try again leads to something spectacular.