Most people think visually and so it often helps to sketch out an idea from its broad sections into the fine detail, arranged around the main topic in a hierarchical way that makes the connections or relationships between them clear. Creating mind maps can help you understand the structure of an assignment or revision topic better, unleash your creativity, and help you to collaborate, solve problems, and think critically.
While you need nothing more than a set of (ideally colourful) pens and paper to draw a mind map, which you can illustrate with sketches if it helps further, there are many software packages available of varying complexity that can help you to map out topics. One example is MindMeister (download MindMeister here), demonstrated in this video.
There are many alternative mind-mapping packages and you should try to find one that suits you, including: