I always open my pushing hand w. four fingers fully spread. I call it "saying hello". Can't take any credit for it, as I started doing that naturally, but that position was reinforced by all the good coaches I've had.
It really is worth trying. In group paddles a few people open to suggestions have tried it, and all of them said it made an immediate improvement in the pressure they felt on their hands, wrists and forearms.
A great forward stroke is not intuitive. One coach said that of 100 people 1 or 2 will come by it naturally.