Start with a square sheet of paper with white-side facing up.
Rotate the paper so it is "diamond" orientation.
Fold paper in half. Unfold.
Fold in the paper so the top-left and top-right edges of the paper meet the central crease.
Fold in the paper so the bottom-left and bottom-right edges of the paper meet the central crease.
Fold the model in half (bottom to top).
Fold the top flap back down: make the crease so only the white part of the paper is showing when you look at the back side of the model (join blue dots). Turn the model over to check on the color of the paper before you make a firm crease.
Fold up the bottom point of the model (join red dots).
Turn over and you're done!