Some safety tips first:
When rotary cutting, always cut away from your body.
Close the protective cover on the rotary cutter every time you put it down. Every. Time. Thank you.
If you have kids in your house, put the rotary cutter up high when you are stopping working with it, even for a short time.
here, if you want to read more about it.
The photo above shows how to line up the ruler along the fold of the fabric, making sure that the cut edge will be a 90 degree angle to the fold. (The fold is lined up with the 1/2" marks near the bottom of the ruler.)
Now I am ready to cut strips. I move the bulk of the fabric over to the left of the ruler, so I can use the ruler to measure the width of the strip I am cutting (2 1/4 inches, here). It doesn't have to be perfectly lined up with the lines on the mat for this. If you are going to be cutting several strips, it might be a good idea to unfold your fabric and check that it is still straight after 4 or 5 cuts.
I also wanted to show how to use the 45 degree line on the ruler to cut the edges for binding strips. Line up several layers of fabric on top of each other.
Place the 45 degree line along the long side of the strip, and cut.here, if you're interested. )
I hope this is helpful! I'd love it if anyone has feedback about this. Does everything make sense? Have I left anything out? Please let me know in the comments.