You probably already know about the fabric, but I've had problems with this period, also, for my customers. I've found that you just have to have the right fabrics. Nothing stiff or crispy. It has to be all soft and drapey or soft and floaty, stiff and crispy fabrics end up looking hideaously bulky in this period.
I had a client who insisted on a lovely but semi-crisp antique satin (in spite of my protests) and we just couldn't make it work.