i don't "appropriately" trim woody's claws, i usually just knick the little sharp tip off the end with my big toe nail clippers. if you want to trim them for real, i'd suggest getting real cat claw trimmers. you can get em at petsmart for dirt cheap. woody is pretty good with her claws though, the tip is all that needs done. yoshimi though...i really need to get some clippers and do something about those little weapons! she tears me up when she kneads in my lap.
i use special clippers to trim my cat's nails, maybe once in 2 weeks. Just the tip, he does a great job of keeping his trim on his sisal posts. I tried just to see what would happen to use my big toe nail clippers, and oh boy, that was a mistake, the nail chipped and small splinters where left behind... so i'm only using the clippers
i used a normal one once, i did not like the results. ralph's nails ended up becoming cracked at the tips. so i decided to buy a cat nail trimmer, it works a lot better, cuts it a lot cleaner, no cracks.