Use a standard A4 or letter sheet
Fold the paper lengthwise in half
Unfold and crease sharply
Fold the top two corners to the center line
Fold the new top edges to the center line again
Fold the plane in half along the center line
Fold the wings down evenly on both sides
Make the wings narrow for speed
Add a small upward fold at the back of each wing
Press all creases firmly
Throw it with a fast, level motion