As well as notions for under the ruler or plastic templates, there are notions for the top of the ruler to help mark your place so you don't cut the wrong size.
Highlighter Tape- I have written about this tape before and love it so much I will again. I am sure this comes from the office supply store (although I've never seen it there). It is coloured clear repositional tape that comes in a variety of colours. You tear off a piece at a convenient length and stick it to the top of your ruler. It marks the cutting line so you don't have to go looking for the right line every time.
Here I have used the tape to highlight the correct size cutting lines on the rulers. I find it more useful on the long ruler but would need blue or orange tape to contrast with the yellow lines on the ruler and with the green cutting mat. I have shown how you can use it to highlight 3 lines in a pattern so you can find your place easily. It helps with the long lists of cutting instructions that start patterns. Knitters and cross-stitchers find it useful for charted patterns.
Qtools introduced this plastic triangles not too long ago. The purple ones on the ruler under the package show how to use them. They are made of a heavier plastic than the tapes so they last much longer. The points of the triangles point to the line you are using and the circle in the centre allows you to see what is under the plastic.
You could use the different colours on one project if you have to cut the same size strips out of several fabrics for a project. I do like these very much!