Israel Regardie's how to draw sigils ... something ... is very basic and simple ;
I assume that is what you want as 'how to draw them ' is simple , but how to 'make them' is a complex mathematical formula
I have books on that , but I am not supposing that is what you meant ? Also I have extensive posts on it ... maybe here , do a search .
Some claim to have a 'savant' power with this ; Ben Franklin could jot them off autiomatically apparently .
His square of 8 is rather different and innovative ;
here is a thing ; with all 'magic squares ' .... 'join the dots ' ie, draw a line from a same reference point ( the center of each square , or for ease in calculation choose, say , the top left hand point of each square ) and draw a line from I to 2 to 3 and so on and then the last number and back to 1 .
What a surprise ! The smaller numbers need this shape rotated and superimposed to make the 'magic square mandala / yantra .
It was an innovation I used to make a 'planetary karmea ' for each altar front ' we set up for each of the planetary rites of Eleusis we used to do . Vivid, electric, grid of energy ... much better than these boring mundane and rather unmagical versions
...
His is J. J. Jain ( an old friend that showed me this join the dots technique ) with Ben Franklin square of 8 with the technique and the color correspondences - of his calculations - mine were differnt colors )
being 8 I painted it for the altar front for our Rite of Mercury ... it even resembles the glyph of Gemini ( whose planetary ruler is Mercury )