This one is so fun to do. You can make the whole tangle without lifting your pencil and then go back and fill in the black shadows. The shadows are what turns it from a lifeless scribble into a 3-dimensional tangle. Tip: Keep the left triangle round (convex) and the right skinny and curving inward (concave.)
This also looks great curvy, but I find it difficult to curve without guidelines.
It also lends itself to decreasing in size as you move from bottom to top.