Step 3: Insert Stiffy joke here
Using Stiffy can be messy, so set up your dummy in the bathtub or on a large drop cloth.
Straight Stiffy works, but I found it was cheaper to stretch it out with equal parts of water and white glue. Just glue and water may also do the trick if you can't get fabric stiffener in your local walmart or craft store.
Mix up your Stiffy and glue and apply it to the clothing with a paint brush. Thoroughly saturate the entire outfit.
While it is still wet, make sure you are happy with how the clothing is hanging on the dummy and then leave it to dry over night.