Start with a rectangular sheet of paper
Fold it in half lengthwise
Unfold it
Fold the top two corners down to the center crease
Fold the new top edges down to the center crease again
Fold the plane in half along the center crease
Fold each wing down to match the bottom edge of the body
Flip the plane over
Fold small wing flaps upward if desired
Adjust the wings and nose for balance
Throw it gently forward