Lay your handkerchief with the point facing up and then take the bottom corner and fold it up to almost meeting the top point.
Then fold the top layer down so that it goes past the bottom of the handkerchief.
Take that same fold and fold it back up towards the top.
Repeat once more by folding down the top layer.
Take that same fold again and fold it back up towards the top.
By this point the folds will be nice and tidy. Now fold the right half of the folded triangle under towards the left.
Rotate the triangle as shown.
Fold the left hand edge over.
Fold the right hand endge over to the left.