If you read the directions for most patterns, the order in which they have you construct a garment goes like this: make the outer shell. Make the lining. Make the inner foundation (if there is one). Attach layers.
No, dear readers. If you want your garment to turn out well, work from the inside out. In the case of my Badgley Mishka gala dress, I started with the inner corselette. Once that was fitted, I made the muslin for the outer garment. The muslin fit completely differently without the corset underneath. It makes sense, doesn’t it? Everything we’ve ever learned about fitting garments says to wear the undergarments you’ll be wearing when the garment is done. And the corselette is the undergarment, right? Well, there you go.
So, I counter the standard instructions with this suggestion. Make any foundation garment first, then make the lining, and only after those are done, make the outer shell. You’ll definitely end up with a better result.