How do I finish/sew necklines and armholes with facings in blouses, dresses and vests?

The colored lines in the pictures show you, in addition to the description, where to sew a seam.

Place the front piece right sides together on the facing and sew the neckline and armholes together. Clip the seam allowance of your armhole and neckline so that the seam allowance will lie nicely in the curve later.

Repeat the same process with the back pieces*, placing them right sides together on the facing and sewing the neckline and armholes together. Clip the seam allowance at the curves. Turn the back pieces right side out and press them well. Important! Do not turn the front piece right side out yet.

The back pieces are turned to the right side of the fabric, while the front piece still has the wrong side of the fabric on the outside.

Now the back piece is inserted into the front piece. You push the back pieces through until the shoulder edges are aligned. Make sure that the armhole edges and the neckline edges are aligned.

Next, sew the shoulder seam together...

and trim the corners!

Now you can pull out the back pieces and iron everything well.

Finally, sew the side seams together. To do this, place the matching sides right sides together, unfolded.

Your top, finished with the facing, is now complete!