When making historical clothing, it is important to remember that they didn't have all the tools that we have today. Also, something that isn't as important now as it was to them was that small waist appearance. This was a huge one for them; to help with this appearance, they made up several different nifty tricks in changing where the seams were.
Dropped shoulders were a characteristic of historical clothing. As you can see in the picture below, my seam is pretty low (please ignore that ugly crease). Plus I just learned that sloping shoulders was a thing back then....this definitely would have helped.
Another was the shoulder seam. No, not the dropped shoulders; this is the seam that connects the front to the back. Instead of being perfectly straight and sitting right on your shoulder, like your t shirt now, they were actually more in the back, sloping downwards. I think this was to also help with the narrow shoulder theory. It's kind of hard to see in this picture, but this is a good example.
One thing I did not know and is actually really helpful is the underarm sleeve seam. Maybe you are supposed to do this on any other garment, I don't know, but what they did was they did not line up the underarm seam with the side seam. Instead they made the underarm seam on the sleeve come more forward; even though those sleeves appear really full, the shortest point is the under seam. So by lining up that under seam, they gave themselves the most room. When I made my dress, I definitely discovered this to be true; when I didn't use this method, I couldn't stretch my arm out all the way! I don't think I have any pictures of this one.
This is one of my favorites: to make their waist appear smaller (and just because it is awesome!) they made the back in several different pieces. My friend says it is called a 'fiddle back'. That is the curved back seam, which I am using on my ball dress! I think they totally look cool, and because of the construction it does make the waist appear smaller. And yes, this is the back of a dress. Not all dresses had them (my wash dress doesn't), but most of the higher fashion ones seemed to.
So there you have it. I'm sure there are some that I am missing, but those were the ones off the top of my head.