Came here to say this. Also, most mind map implementations are actually spider diagrams which (while useful) are not mind maps, the point of a mind map is the label the line and not the node.
Use Your Head by Tony Buzan is totally worth a read and is how I learned mind mapping 22 years ago. I can still remember the rough layout and shape of many of the mind maps I made for GCSE and A-level revision. Iām 100% certain that reading that book and sticking to his methodologies added one or two letter grades to my exams at that age.