Stick some non - sliding dots or dots of sandpaper on the underside of your rule. Make sure your blade is sharp. Don't try to cut through too many layers at once. Put even pressure with the fingertips of your hand pushing down in centre of the rule. Don't lay your hand flatly on the rule. Hope this works for you. If you need more assistance, you can buy a suction cup that is like a door handle, to put onto your rule and press down on that.
One other lady showed, in a recent post, how she uses clamps to hold the rule down.