I don’t think there are any specific guidelines to follow. It’s completely random and what you feel like drawing. If you google the word mandela in images you can see examples of some. Mine are pretty simple, not as complex as a lot. You can color them in if you want or just stay with the black and white. I use a drawing compass to make my main circles and then just draw things inside the circles. Then I take a black sharpie marker and go over the lines and may fill in a couple of sections with the black. I like the black and white. If I could figure out how to post a picture of the ones I’ve done then I could show you mine.
This is certainly one of my most favorite things to draw/paint. Usually my art has some type of mandela or mandela-esque part within it. It’s a very therapeutic subject because there is a pattern or sorts to follow; however, also a lot of room for creativity.