I use a program called Xmind, on a mac. There are lots of different software products out there that do it. Some are more graphical than others.
For me I try and keep it as simple as possible, and keep the text as short as possible. Less is more mindset. Try and make it flow as if it is how you think, or for me how I compartment ideas, concepts, steps to a problem set. Sort of like WBS (work breakdown structure) in Project Management, but much simpler.
Check out some of my other postings on Medium for more sample.
Here too is one I did for redecorating our house.
