@sarahbecan “rightie tightie“ fails when you're dealing with a nut or bolt facing towards you on the other side of an object - i.e., when you're reaching round something with a screwdriver, spanner or socket. Turning the top to the right then untightens it.

You can try imaging you're on the other side, working out which way you'd turn the fastener then try doing that from your side but that is likely to have a higher than zero failure rate.

Having struggled with this quite a few times I've come up with “right away”: turning the top of the (conventionally threaded) fastener to the right makes it move away from you.