Staggered stance to open the hips and shoulders so that you can look downhill without craning your neck.
You will naturally be stronger on one side, that’s the side you will probably return to most and learn to carve first on. On that comfortable side just seek the feeling of switching from flat base to edge, and try little by little to get up on each edge, and just like carving forwards: flat base -> one edge -> back to flat base -> next edge.
you will definitely feel awkward, hook up, and scare yourself from time to time.
once you have a very basic feeling of edge to edge, start working looking over both shoulders. Work on switching the staggered stance with flat bases, and then try to play with the edges a little.
start on your dominant side, look uphill, point straight up fall-line with the uphill arm and start bringing it down the hill, opening your shoulders, hips, and vision to the next side, making that the downhill ski/hip/shoulder/side.
hope this helps!! I LOVE skiing backwards and it’s some of the most fun you can have on piste and it opens up a whole other realm of tricks and feelings, and you can practice it on any trail on the hill!