i've had invisagrip on my rulers for years- it helps- it really takes learning to hold your ruler - nothing is (fool proof) for keeping your ruler from sliding beyond learning the best way to use it.
(spider web) your fingers out across the top of the ruler with your pinkie on the outside-along the side of the ruler-on the table-holding the ruler secure- and as long as you have a nice sharp blade in your cutter you do not have to push hard along the edge of the ruler- it just takes some practice & will become (natural) to you as you do it more & more- with better results all the time- i've tried lots of different dots, sandpaper, felt, rubber...nothing has worked any better than the invisigrip- and i prefer it over the other options because it is see through- all the other items either cover up or distort lines somewhere.