Step 1:
This paper is 20x20 centimeters. Prefold and cut in three parts of the same size.
Then glue the parts together into one long rectangle.

Step 6:
Fold over the two upper lines and make the dress the right length by folding over the two lines below.

Step 5:
Fold over these two lines

Step 3:
Fold over these four lines, use the prefolded centerline as guidance.

Step 2:
Prefold in half

Step 4:
Prefold over this line

Step 7:
Fold in half

Step 8:
Press inwards around the waist, use glue or tape if necessary.

Press the model inwards on these places, see arrows.
And glue or tape the edges together, see marked areas.....   Done!
This is an Origami video tutorial for folding the Carmen Dress:

Pictures: Paper dollhouse office and fashion dolls wearing a white and purple carmen dress (by Joost Langeveld)