I haven't added grippy things to my rulers, and occasionally I get slippage and cursing, but two things that I have found useful: a
ruler with a lip at the end that goes over the top edge of your mat (so you can gently pull backwards on it to help keep it steady, like a T-square), and leaning on my ruler with my whole forearm when I am cutting slippery fabrics or multiple layers. This last tip can be tough on your back if you are doing a lot of cutting, but does work well!
I also agree that with practice you will find ways that work for you.
Good luck!
Alison