Use a standard letter-size sheet of paper
Fold the paper lengthwise in half, then unfold it
Fold the top two corners to the center crease
Fold the new top edges to the center crease again
Fold the plane in half along the center crease
Fold each wing down evenly
Keep both wings symmetrical
Make the wings slightly angled upward
Press all folds firmly
Trim or adjust the nose for balance if needed
Add small winglets at the tips if desired
Test throw with a smooth, level motion
Make small adjustments after each test flight