Learn to work with interlinings, and not just the crappy "interfacing" sold at standard fabric stores. The book "Bridal Couture" by Susan Khalje was invaluable in explaining different interlinings and what they could do. I swear by silk organza in EVERYTHING.
Kendra Van Cleave
Know your interfacings - which type to use with your given fabric.
I’m in absolute agreement on this one. If you want to know the great big dirty secret that professional seamstresses and costumiers are keeping from you, we’re here to tell you that it’s interlinings.
Interlinings aren’t the same thing as interfacings. An interlining is an extra layer of fabric laid between the fashion fabric and lining that changes the way that the fashion fabric behaves. You can use interlinings to give a flimsy fabric extra body, to stop creasing, to make a pale fabric denser or more opaque, and to stop the edges of the seam allowances showing on the outside of the garment after you’ve pressed the seams.
Many different fabrics make good interlinings, but as Kendra says, the most common and most useful is silk organza, which is light, natural and gives just a hint of body without stiffness, stopping your costume from drooping like a wet (and very home-made) lettuce. Use it by cutting all your fashion fabric pieces in silk organza as well as the fashion fabric, and then basting the two together, so that you can treat them as one.
Interfacings also lie unseen between fashion fabric and lining, but they appear in small areas only – around a neckline, a cuff, at the front of a jacket. They give stiffness and shape where it’s most needed. As Tanya says, different interfacings are necessary for different types of fabric: clearly you’ll need to interface an Edwardian muslin blouse with something different from a heavy wool surcoat.
Here’s another tip: don’t just consider the manufactured interfacings that the store assistant shows you. (In fact, many experts don’t use these interfacings at all.) Get curious. Who are the most accomplished users of interfacings? The answer has to be bespoke tailors, who need to sculpt their suits into perfectly crafted masterpieces for every distinguished client. How can you find out what sort of interfacings they use?