Rustic,
If you don't need to do alot of arrow cutting, the helpful tips above will work fine. (I've tried them all!).
Carbons can be touchy, both cutting and tuning. (A 1/4" can make a difference). Sometimes, multiple cuts (trimming) might be necessary to get 'em just right. I finally went ahead and bought an Arrow Saw, a Weston from Bowhunters Superstore. For less than $120 inc. shipping, it is a good saw that I can use confidently & quickly to cut my arrows. Already feel like it's paid for itself.