I've had lots of questions about this technique. Hopefully this post will answer all of them.
I am using the Be Still My Heart block from Esther's Heart's Desire BOM. This pattern is free until March 15th, when she will offer block 2 of the Mystery Block of the Month free for a month. It's a good block to practice this technique on since there are long, sweeping turns rather than a lot of fussy inside & outside points.
I like to start stitching in the middle of a straight section since it's sometimes hard to get started and do an inside or outside point at the same time.
On a straight section like this, I like to turn under 1-1.5" before I start to stitch. Grab the seam allowance that you are going to turn under with the tip of your needle.
Then just stitch-away. My stitches are typically 5mm apart on straight sections and as close as 3mm on inside and outside points.
I mark the outline of the piece with large pins. In this case, I only need to mark 2 sides b/c the outside green petal marks the outside (left side in the picture.)
That way, when I flip it to the back to baste, I can see that the pins are outside the design area and I have enough fabric to cover the shape. Also, with the pins on the opposite side from the basting, the thread doesn't get caught while you are stitching.
I make small corrections sometimes when basting too. The line I drew on the right, seemed to get narrow, so I moved the basting line to the inside of the drawn line. I'll make corrections to my wonky stitching line when I trim the shape.
So, what do you think? Are you ready to try?