After the front and back of the jacket were sewed together, the sleeves went on. This sleeve is not set-in and has a very flat line where the shoulder attaches to the body of the jacket. Consequently, I can get away with fewer pins than I normally use instead of basting, to attach the sleeve before I sew it.
Once it is sewed on (and always after ironing), I clip one half of the seam allowance to about 1/4 inch and fold the other half over it in a proper flat fell. In my case, I prefer to clip the seam allowance that belongs to the body of the jacket and fold over the seam allowance that belongs to the sleeve. There is no seam in the sleeve and it generally lies flatter that way.
In the next photo, the sleeve is on the right. You can see that this sleeve seam allowance is folded over, on the left of the seam itself. I am sewing the fold down onto the body of the jacket to the left of the seam.
In the next photo, you can see the modified flat fell of the shoulder seam in the left third of the picture (I have folded each seam allowance under and sewed it down, so you get two lines of topstitching). You can see the shoulder seam and the proper flat fell of the shoulder seam (although I have only stitching down the fold and have not made a second line of stitching down the seam line, as I would on a jean jacket). I folded up the right side of this assembly so you could see the underside (the wrong side) of the sleeve shoulder seam all in one photo. That’s why it looks a little odd.
Finally, I am showing the inside of the skirt where I have machine sewed down the facing to the body of the skirt. I find that hand sewing the facing is rarely satisfactory as the hand sewing comes undone after a few washings. If you sew from the right side of the skirt into the gutter of a seam, you can hardly notice it and then the facing stays put. I left the raw edge of the facing the way it was. It will fray some after washing but not enough to irritate me and this way, there will not be an obvious line on the outside of the skirt, as there would be if I had folded up the raw edge of the facing.