Trial and error. Learn as you go. Learn things the hard way. Yup! That's me! This loose gown coat thingy is finally starting to look like something but, um, that something is crap! I thought I was being so clever and saving myself some time. I pinned all the trim to the black shell last night and machine stitched it all down along the inside edge. Then I folded in the edges of both the shell and the lining and machine stitched them together catching the outer edge of the trim at the same time. What may (or may not) have been a good idea in theory doesn't look so good in practice. I need to pick it all loose, hem the shell and lining seperately, and sew the front edges together by hand. It is good enough to wear in Frankenmuth if I run out of time to redo it before we go but I know I'll not be happy with it until I fix these things. For now I'm going to move on to the sleeves so it will actually be wearable.
ETA: While it still would have looked better if I had taken the time to handstitch it, it does look much better and the hem hangs correctly after a pressing. Yes I am my own worst critic.