little sand paper dots or plastic dot that go on the back of the ruler help. Someone also mentioned making their own by using a hot glue gun and placing small amounts on the ruler back. most rulers will move if you don't have something to create friction to keep it from moving

I have some smaller square rulers and generally rough-cut my fussy bits. Then I square them up using the smaller rulers.

That would be my suggestion, too -- in addition to adding dots of some sort to your ruler. But I've also been known to trace the design & cut it out with scissors.

I cut out a section larger than I want and then use a square ruler to center the motif and trim it to the size I want.

An alternative to the bought sandpaper dots is: clear nail polish sprinkled with salt, I let mine dry overnight on my island. It works great in my opinion.

I haven't checked my rulers but I am pretty sure that I have a 4 1/2" square that is great for fussy cutting.

I use my square template, draw a line around and cut with scissors. Sometimes scissors are just right. Love the sharp pizza cutter idea, but all the fussy cuts i do, nope. I use the scarp scissors. :0)

You guys are so smart. Some really good ideas for how to make sure you cut the same motif with every piece.

Out of sheer frustration once, I coated the bottom of a ruler with rubber cement, thinking that since it was a little tacky when dry, it would work well. It took under 5 minutes to dry and clings like nothing else!!!! I love it and use it often. It simply DOES NOT MOVE when in place! After many uses, it loses its tackiness due to lint sticking to the cement, so you just rub it off with your finger and re-coat.