Step 1:
The Origami paper is 30x30 centimeters.
Fold in half

Step 6:
Prefold the lower (prefolded) line to the prefolded centerline.

Step 5:
Prefold over these two lines, use the prefolded squares pattern as guidance.
Then unfold the model.

Step 2:
Prefold in half, then fold both edges to the prefolded centerline.

Step 4:
Prefold in half, then prefold both edges to the centerline.

Step 3:
Fold to the centerline, then unfold the folds of steps 2 and 3.

Step 10:
Here a part of step 9 is done, the arrow shows where the center edge goes.

Step 8:
Fold the three edges (prefolded mountain-folds) against each other.

Step 9:
Fold these (prefolded) edges upwards

Step 7:
Fold the edges backwards over the prefolded lines, not completely backwards yet. That's possible in steps 9 and 10

Step 16:
Fold over these two lines.

Step 15:
Fold this edge to the left, making the model flat again.

Step 12:
Fold the edge downwards, the right line is already prefolded.
This will be the back of the dress.

Step 11:
Now the model is completely flat again.
Open the upper part.

Step 14:
Fold the upper edge downwards

Step 13:
Close the model again

Step 17:
Fold over these two short lines.

Step 18:
Fold the lower edges to the inside, do the same on the backside.

Step 19:
I used a fashion doll of about 30 centimeters, glue or tape the edges together, see marked areas.