TSR Bleat - Sewing Techniques
Always sew on a flat surface, like a table. Be sure to keep your braids up on the table, don't put them on the floor. If they are on the floor, just enough tension could be added as you sew to make your work pucker. Another tip to make your rug lay flat is to nestle the braids into the rug, don't pull or stretch the braid as you sew it.
Be sure to sew on the edge of the braid, you may have to pick up your work to see where to place your stitch, keep stitches even on the straight sides, but on the curves make stitches smaller on the rug side and a little longer on the braid side to ease into the curve. This technique helps your rug lay flat.
To know where to change from even stitches to smaller/longer stitches look for the point at the end of the very first round (right hand above), draw a line straight down to see where the short/long stitches should start (left hand above). Start doing short/long stitches starting at the finger of the left hand all the way around to the corresponding point on the other side of the curve.