This is an unstructured overcoat, meaning that it doesn’t have a lining and no shaping like shoulder pads or heavy interfacing. I will give you some tips below on using some light interfacing, especially for the front facing pieces.
Some design details that you don’t want to miss:
I made the sleeve with a raised sleeve cap so it should be set in from the tip of your shoulder a little bit, meaning that the shoulder seam is meant to be a little shorter. When you are tissue fitting don’t correct this!
This coat has a 3 piece sleeve because your arm doesn’t hang stick straight so why should your sleeve? It bends gently at the elbow and is shaped with darts and a curved over-arm seam. Make sure not to press it down flat. Use pressing tools to press your seams open. Then to one side to do your topstitching.
Topstitching is optional, but suggested~ it will keep the edges of your overcoat flat and make the seams stronger.