@atatassault @sarahbecan that's how I've always understood it.
You put your right hand on the screw, this means your thumb is pointing the same way as the screw point. Fingers curled round the screw tells you which way to tighten. Righty tighty. Clockwise, as you say.
Left hand is opposite, thumb down to point. Curl fingers. Lefty loosey. Widdershins.