I felt like I was hijacking Teen's beautiful jelly roll rug post by discussing mechanics, so here's what I offer after making a few rugs:
- https://www.youtube.com/watch?v=Y8xblarkuBg&t=1023s is my go to video
- iron after 2 times around, then let cool
- when stitching rug around the curves, I gently push/scrunch the rope(just a tiny bit) to help outside edge to lie flatter
- when creating rope, Wonder clip an area ahead of stitching
- fold bottom edge of JR and clip
- fold top edge to meet in the middle and place clips between bottom edge's clips
- when you join those edges together, just lift off each clip and reattach to include both edges
- hope pictures help