Tools

Activity diagram: a method of representing a process model to represent how a business operates
Affinity chart: synthesizes large amounts of data by finding relationships/themes between ideas to discover common themes, connections, or root causes
Context diagram: show the interactions between a system and other actors (external factors) with which the system is designed to interface
Fishbone diagram: illustrates the cause of a specific event, typically used for quality control or root causes
Prioritization techniques: MoSCoW, priority matrix, priority scale, voting
Process and data modelling tools: process flow diagram, cross-functional process flow diagram, data flow diagram, state diagram, entity-relationship diagram (ERD), class diagram, data dictionary
Identifying roles and responsibilities: (DRACI/DRASCI)
Use case: tool for capturing functional requirements of the system

Additional information can be acquired through the Business Analysis Body of Knowledge (BABOK) and from the Project Management Body of Knowledge (PMBOK).