This tutorial focuses on introducing participants to Annif, a multilingual automated subject indexing tool that can enhance for example a library's metadata generation system. Better metadata contributes to easier discoverability, emphasizing the impact of both Annif and this tutorial on information accessibility, reusability and retrieval as well. Through hands-on exercises, use case presentations and demos, attendees gain practical experience in setting up Annif, training algorithms with sample data, and utilizing the tool to generate subject suggestions for new documents. The tutorial covers basic and advanced usage scenarios and allows participants to deepen their understanding and proficiency in implementing Annif for efficient metadata production in library systems. We will introduce and demonstrate the use of Annif in institutional repositories. The tutorial is aimed at anyone with an interest in library automation including developers and metadata librarians.