Information retrieval begins with defining the research topic or problem. As an information seeker, you will have to clarify to yourself what information you are looking for and where you may be able to find it. When planning your information retrieval, the following research questions may help you define your topic:
After piecing together your topic, consider concepts, terms and words which describe it. Remember the alternatives (synonyms, abbreviations).
Mind maps etc. offer ways of specifying and outlining the research problem. A mind map is a tree-like figure where the topic is divided into sections and further into their subsections.
Source: XMind 6
Finto AI suggests subjects for a given text. It's based on Annif, a tool for automated subject indexing.