Required:
1 x pillow-case;
Temporary padding (I used a couple of shirts from my laundry-basket);
Full petticoat w/ solid band;
In absence of petticoat, a belt under your skirt;
A full skirt;
Optional safety pins.
Process:
Stuff the pillow-case about a third full;
Tuck the stuffed pillow-case around your waist-band so the full part is on the inside and at least half of the un-stuffed part is on the outside;
Pin for extra security;
Drape the skirt over;
Swish.
Notes:
This gives a minor, elegant bump that doesn’t noticeably affect the back-length of the skirt. Another option for stuffing is a two-litre plastic bottle with the neck cut off. For more aggressive silhouettes, it’s probably best to use a proper pattern (Truly Victorian is a good pattern company with a lot of variety) and tailor your dress to the underwear.
It took much longer to write this than it did to do it.